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Reformat the C# codes.

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Disable creating new line before open brace.
This commit is contained in:
krahets 2023-04-23 03:03:12 +08:00
parent ac6eece4f3
commit 73dcb4cea9
49 changed files with 561 additions and 1135 deletions
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6
codes/csharp/.editorconfig Normal file
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@ -0,0 +1,6 @@
# CSharp formatting rules
[*.cs]
csharp_new_line_before_open_brace = none
csharp_new_line_before_else = false
csharp_new_line_before_catch = false
csharp_new_line_before_finally = false

45
codes/csharp/chapter_array_and_linkedlist/array.cs
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@ -6,11 +6,9 @@ using NUnit.Framework;
namespace hello_algo.chapter_array_and_linkedlist;
public class array
{
public class array {
/* 随机返回一个数组元素 */
public static int randomAccess(int[] nums)
{
public static int randomAccess(int[] nums) {
Random random = new();
// 在区间 [0, nums.Length) 中随机抽取一个数字
int randomIndex = random.Next(nums.Length);
@ -20,13 +18,11 @@ public class array
}
/* 扩展数组长度 */
public static int[] extend(int[] nums, int enlarge)
{
public static int[] extend(int[] nums, int enlarge) {
// 初始化一个扩展长度后的数组
int[] res = new int[nums.Length + enlarge];
// 将原数组中的所有元素复制到新数组
for (int i = 0; i < nums.Length; i++)
{
for (int i = 0; i < nums.Length; i++) {
res[i] = nums[i];
}
// 返回扩展后的新数组
@ -34,11 +30,9 @@ public class array
}
/* 在数组的索引 index 处插入元素 num */
public static void insert(int[] nums, int num, int index)
{
public static void insert(int[] nums, int num, int index) {
// 把索引 index 以及之后的所有元素向后移动一位
for (int i = nums.Length - 1; i > index; i--)
{
for (int i = nums.Length - 1; i > index; i--) {
nums[i] = nums[i - 1];
}
// 将 num 赋给 index 处元素
@ -46,36 +40,29 @@ public class array
}
/* 删除索引 index 处元素 */
public static void remove(int[] nums, int index)
{
public static void remove(int[] nums, int index) {
// 把索引 index 之后的所有元素向前移动一位
for (int i = index; i < nums.Length - 1; i++)
{
for (int i = index; i < nums.Length - 1; i++) {
nums[i] = nums[i + 1];
}
}
/* 遍历数组 */
public static void traverse(int[] nums)
{
public static void traverse(int[] nums) {
int count = 0;
// 通过索引遍历数组
for (int i = 0; i < nums.Length; i++)
{
for (int i = 0; i < nums.Length; i++) {
count++;
}
// 直接遍历数组
foreach (int num in nums)
{
foreach (int num in nums) {
count++;
}
}
/* 在数组中查找指定元素 */
public static int find(int[] nums, int target)
{
for (int i = 0; i < nums.Length; i++)
{
public static int find(int[] nums, int target) {
for (int i = 0; i < nums.Length; i++) {
if (nums[i] == target)
return i;
}
@ -83,15 +70,13 @@ public class array
}
/* 辅助函数,数组转字符串 */
public static string toString(int[] nums)
{
public static string toString(int[] nums) {
return string.Join(",", nums);
}
[Test]
public static void Test()
{
public static void Test() {
// 初始化数组
int[] arr = new int[5];
Console.WriteLine("数组 arr = " + toString(arr));

24
codes/csharp/chapter_array_and_linkedlist/linked_list.cs
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@ -7,19 +7,16 @@ using NUnit.Framework;
namespace hello_algo.chapter_array_and_linkedlist;
public class linked_list
{
public class linked_list {
/* 在链表的节点 n0 之后插入节点 P */
public static void insert(ListNode n0, ListNode P)
{
public static void insert(ListNode n0, ListNode P) {
ListNode? n1 = n0.next;
P.next = n1;
n0.next = P;
}
/* 删除链表的节点 n0 之后的首个节点 */
public static void remove(ListNode n0)
{
public static void remove(ListNode n0) {
if (n0.next == null)
return;
// n0 -> P -> n1
@ -29,10 +26,8 @@ public class linked_list
}
/* 访问链表中索引为 index 的节点 */
public static ListNode? access(ListNode head, int index)
{
for (int i = 0; i < index; i++)
{
public static ListNode? access(ListNode head, int index) {
for (int i = 0; i < index; i++) {
if (head == null)
return null;
head = head.next;
@ -41,11 +36,9 @@ public class linked_list
}
/* 在链表中查找值为 target 的首个节点 */
public static int find(ListNode head, int target)
{
public static int find(ListNode head, int target) {
int index = 0;
while (head != null)
{
while (head != null) {
if (head.val == target)
return index;
head = head.next;
@ -56,8 +49,7 @@ public class linked_list
[Test]
public void Test()
{
public void Test() {
// 初始化链表
// 初始化各个节点
ListNode n0 = new ListNode(1);

12
codes/csharp/chapter_array_and_linkedlist/list.cs
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@ -8,11 +8,9 @@ using NUnit.Framework;
namespace hello_algo.chapter_array_and_linkedlist;
public class list
{
public class list {
[Test]
public void Test()
{
public void Test() {
/* 初始化列表 */
int[] numbers = new int[] { 1, 3, 2, 5, 4 };
@ -49,15 +47,13 @@ public class list
/* 通过索引遍历列表 */
int count = 0;
for (int i = 0; i < list.Count(); i++)
{
for (int i = 0; i < list.Count(); i++) {
count++;
}
/* 直接遍历列表元素 */
count = 0;
foreach (int n in list)
{
foreach (int n in list) {
count++;
}

51
codes/csharp/chapter_array_and_linkedlist/my_list.cs
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@ -9,34 +9,29 @@ using NUnit.Framework;
namespace hello_algo.chapter_array_and_linkedlist;
/* 列表类简易实现 */
class MyList
{
class MyList {
private int[] nums; // 数组（存储列表元素）
private int numsCapacity = 10; // 列表容量
private int numsSize = 0; // 列表长度（即当前元素数量）
private int extendRatio = 2; // 每次列表扩容的倍数
/* 构造方法 */
public MyList()
{
public MyList() {
nums = new int[numsCapacity];
}
/* 获取列表长度（即当前元素数量）*/
public int size()
{
public int size() {
return numsSize;
}
/* 获取列表容量 */
public int capacity()
{
public int capacity() {
return numsCapacity;
}
/* 访问元素 */
public int get(int index)
{
public int get(int index) {
// 索引如果越界则抛出异常，下同
if (index < 0 || index >= numsSize)
throw new IndexOutOfRangeException("索引越界");
@ -44,16 +39,14 @@ class MyList
}
/* 更新元素 */
public void set(int index, int num)
{
public void set(int index, int num) {
if (index < 0 || index >= numsSize)
throw new IndexOutOfRangeException("索引越界");
nums[index] = num;
}
/* 尾部添加元素 */
public void add(int num)
{
public void add(int num) {
// 元素数量超出容量时，触发扩容机制
if (numsSize == numsCapacity)
extendCapacity();
@ -63,16 +56,14 @@ class MyList
}
/* 中间插入元素 */
public void insert(int index, int num)
{
public void insert(int index, int num) {
if (index < 0 || index >= numsSize)
throw new IndexOutOfRangeException("索引越界");
// 元素数量超出容量时，触发扩容机制
if (numsSize == numsCapacity)
extendCapacity();
// 将索引 index 以及之后的元素都向后移动一位
for (int j = numsSize - 1; j >= index; j--)
{
for (int j = numsSize - 1; j >= index; j--) {
nums[j + 1] = nums[j];
}
nums[index] = num;
@ -81,14 +72,12 @@ class MyList
}
/* 删除元素 */
public int remove(int index)
{
public int remove(int index) {
if (index < 0 || index >= numsSize)
throw new IndexOutOfRangeException("索引越界");
int num = nums[index];
// 将索引 index 之后的元素都向前移动一位
for (int j = index; j < numsSize - 1; j++)
{
for (int j = index; j < numsSize - 1; j++) {
nums[j] = nums[j + 1];
}
// 更新元素数量
@ -98,8 +87,7 @@ class MyList
}
/* 列表扩容 */
public void extendCapacity()
{
public void extendCapacity() {
// 新建一个长度为 numsCapacity * extendRatio 的数组，并将原数组拷贝到新数组
System.Array.Resize(ref nums, numsCapacity * extendRatio);
// 更新列表容量
@ -107,23 +95,19 @@ class MyList
}
/* 将列表转换为数组 */
public int[] toArray()
{
public int[] toArray() {
// 仅转换有效长度范围内的列表元素
int[] nums = new int[numsSize];
for (int i = 0; i < numsSize; i++)
{
for (int i = 0; i < numsSize; i++) {
nums[i] = get(i);
}
return nums;
}
}
public class my_list
{
public class my_list {
[Test]
public void Test()
{
public void Test() {
/* 初始化列表 */
MyList list = new MyList();
/* 尾部添加元素 */
@ -152,8 +136,7 @@ public class my_list
Console.WriteLine("将索引 1 处的元素更新为 0 ，得到 list = " + string.Join(",", list.toArray()));
/* 测试扩容机制 */
for (int i = 0; i < 10; i++)
{
for (int i = 0; i < 10; i++) {
// 在 i = 5 时，列表长度将超出列表容量，此时触发扩容机制
list.add(i);
}

15
codes/csharp/chapter_backtracking/preorder_traversal_i_compact.cs
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@ -10,19 +10,15 @@ using System.IO;
namespace hello_algo.chapter_backtracking;
public class preorder_traversal_i_compact
{
public class preorder_traversal_i_compact {
static List<TreeNode> res;
/* 前序遍历：例题一 */
static void preOrder(TreeNode root)
{
if (root == null)
{
static void preOrder(TreeNode root) {
if (root == null) {
return;
}
if (root.val == 7)
{
if (root.val == 7) {
// 记录解
res.Add(root);
}
@ -31,8 +27,7 @@ public class preorder_traversal_i_compact
}
[Test]
public void Test()
{
public void Test() {
TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
Console.WriteLine("\n初始化二叉树");
PrintUtil.PrintTree(root);

18
codes/csharp/chapter_backtracking/preorder_traversal_ii_compact.cs
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@ -9,22 +9,18 @@ using NUnit.Framework;
namespace hello_algo.chapter_backtracking;
public class preorder_traversal_ii_compact
{
public class preorder_traversal_ii_compact {
static List<TreeNode> path;
static List<List<TreeNode>> res;
/* 前序遍历：例题二 */
static void preOrder(TreeNode root)
{
if (root == null)
{
static void preOrder(TreeNode root) {
if (root == null) {
return;
}
// 尝试
path.Add(root);
if (root.val == 7)
{
if (root.val == 7) {
// 记录解
res.Add(new List<TreeNode>(path));
}
@ -35,8 +31,7 @@ public class preorder_traversal_ii_compact
}
[Test]
public void Test()
{
public void Test() {
TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
Console.WriteLine("\n初始化二叉树");
PrintUtil.PrintTree(root);
@ -47,8 +42,7 @@ public class preorder_traversal_ii_compact
preOrder(root);
Console.WriteLine("\n输出所有根节点到节点 7 的路径");
foreach (List<TreeNode> path in res)
{
foreach (List<TreeNode> path in res) {
PrintUtil.PrintList(path.Select(p => p.val).ToList());
}
}

18
codes/csharp/chapter_backtracking/preorder_traversal_iii_compact.cs
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@ -9,23 +9,19 @@ using NUnit.Framework;
namespace hello_algo.chapter_backtracking;
public class preorder_traversal_iii_compact
{
public class preorder_traversal_iii_compact {
static List<TreeNode> path;
static List<List<TreeNode>> res;
/* 前序遍历：例题三 */
static void preOrder(TreeNode root)
{
static void preOrder(TreeNode root) {
// 剪枝
if (root == null || root.val == 3)
{
if (root == null || root.val == 3) {
return;
}
// 尝试
path.Add(root);
if (root.val == 7)
{
if (root.val == 7) {
// 记录解
res.Add(new List<TreeNode>(path));
}
@ -36,8 +32,7 @@ public class preorder_traversal_iii_compact
}
[Test]
public void Test()
{
public void Test() {
TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
Console.WriteLine("\n初始化二叉树");
PrintUtil.PrintTree(root);
@ -48,8 +43,7 @@ public class preorder_traversal_iii_compact
preOrder(root);
Console.WriteLine("\n输出所有根节点到节点 7 的路径，且路径中不包含值为 3 的节点");
foreach (List<TreeNode> path in res)
{
foreach (List<TreeNode> path in res) {
PrintUtil.PrintList(path.Select(p => p.val).ToList());
}
}

36
codes/csharp/chapter_backtracking/preorder_traversal_iii_template.cs
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@ -9,54 +9,44 @@ using NUnit.Framework;
namespace hello_algo.chapter_backtracking;
public class preorder_traversal_iii_template
{
public class preorder_traversal_iii_template {
/* 判断当前状态是否为解 */
static bool isSolution(List<TreeNode> state)
{
static bool isSolution(List<TreeNode> state) {
return state.Count != 0 && state[^1].val == 7;
}
/* 记录解 */
static void recordSolution(List<TreeNode> state, List<List<TreeNode>> res)
{
static void recordSolution(List<TreeNode> state, List<List<TreeNode>> res) {
res.Add(new List<TreeNode>(state));
}
/* 判断在当前状态下，该选择是否合法 */
static bool isValid(List<TreeNode> state, TreeNode choice)
{
static bool isValid(List<TreeNode> state, TreeNode choice) {
return choice != null && choice.val != 3;
}
/* 更新状态 */
static void makeChoice(List<TreeNode> state, TreeNode choice)
{
static void makeChoice(List<TreeNode> state, TreeNode choice) {
state.Add(choice);
}
/* 恢复状态 */
static void undoChoice(List<TreeNode> state, TreeNode choice)
{
static void undoChoice(List<TreeNode> state, TreeNode choice) {
state.RemoveAt(state.Count - 1);
}
/* 回溯算法：例题三 */
static void backtrack(List<TreeNode> state, List<TreeNode> choices, List<List<TreeNode>> res)
{
static void backtrack(List<TreeNode> state, List<TreeNode> choices, List<List<TreeNode>> res) {
// 检查是否为解
if (isSolution(state))
{
if (isSolution(state)) {
// 记录解
recordSolution(state, res);
return;
}
// 遍历所有选择
foreach (TreeNode choice in choices)
{
foreach (TreeNode choice in choices) {
// 剪枝：检查选择是否合法
if (isValid(state, choice))
{
if (isValid(state, choice)) {
// 尝试：做出选择，更新状态
makeChoice(state, choice);
List<TreeNode> nextChoices = new List<TreeNode>() { choice.left, choice.right };
@ -68,8 +58,7 @@ public class preorder_traversal_iii_template
}
[Test]
public void Test()
{
public void Test() {
TreeNode root = TreeNode.ListToTree(new List<int?> { 1, 7, 3, 4, 5, 6, 7 });
Console.WriteLine("\n初始化二叉树");
PrintUtil.PrintTree(root);
@ -80,8 +69,7 @@ public class preorder_traversal_iii_template
backtrack(new List<TreeNode>(), choices, res);
Console.WriteLine("\n输出所有根节点到节点 7 的路径，要求路径中不包含值为 3 的节点");
foreach (List<TreeNode> path in res)
{
foreach (List<TreeNode> path in res) {
PrintUtil.PrintList(path.Select(p => p.val).ToList());
}
}

18
codes/csharp/chapter_binary_search/binary_search.cs
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@ -8,16 +8,13 @@ using NUnit.Framework;
namespace hello_algo.chapter_binary_search;
public class binary_search
{
public class binary_search {
/* 二分查找（双闭区间） */
static int binarySearch(int[] nums, int target)
{
static int binarySearch(int[] nums, int target) {
// 初始化双闭区间 [0, n-1] ，即 i, j 分别指向数组首元素、尾元素
int i = 0, j = nums.Length - 1;
// 循环，当搜索区间为空时跳出（当 i > j 时为空）
while (i <= j)
{
while (i <= j) {
int m = (i + j) / 2; // 计算中点索引 m
if (nums[m] < target) // 此情况说明 target 在区间 [m+1, j] 中
i = m + 1;
@ -31,13 +28,11 @@ public class binary_search
}
/* 二分查找（左闭右开） */
static int binarySearch1(int[] nums, int target)
{
static int binarySearch1(int[] nums, int target) {
// 初始化左闭右开 [0, n) ，即 i, j 分别指向数组首元素、尾元素+1
int i = 0, j = nums.Length;
// 循环，当搜索区间为空时跳出（当 i = j 时为空）
while (i < j)
{
while (i < j) {
int m = (i + j) / 2; // 计算中点索引 m
if (nums[m] < target) // 此情况说明 target 在区间 [m+1, j) 中
i = m + 1;
@ -51,8 +46,7 @@ public class binary_search
}
[Test]
public void Test()
{
public void Test() {
int target = 6;
int[] nums = { 1, 3, 6, 8, 12, 15, 23, 67, 70, 92 };

45
codes/csharp/chapter_computational_complexity/space_complexity.cs
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@ -9,74 +9,62 @@ using NUnit.Framework;
namespace hello_algo.chapter_computational_complexity;
public class space_complexity
{
public class space_complexity {
/* 函数 */
static int function()
{
static int function() {
// do something
return 0;
}
/* 常数阶 */
static void constant(int n)
{
static void constant(int n) {
// 常量、变量、对象占用 O(1) 空间
int a = 0;
int b = 0;
int[] nums = new int[10000];
ListNode node = new ListNode(0);
// 循环中的变量占用 O(1) 空间
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
int c = 0;
}
// 循环中的函数占用 O(1) 空间
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
function();
}
}
/* 线性阶 */
static void linear(int n)
{
static void linear(int n) {
// 长度为 n 的数组占用 O(n) 空间
int[] nums = new int[n];
// 长度为 n 的列表占用 O(n) 空间
List<ListNode> nodes = new();
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
nodes.Add(new ListNode(i));
}
// 长度为 n 的哈希表占用 O(n) 空间
Dictionary<int, string> map = new();
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
map.Add(i, i.ToString());
}
}
/* 线性阶（递归实现） */
static void linearRecur(int n)
{
static void linearRecur(int n) {
Console.WriteLine("递归 n = " + n);
if (n == 1) return;
linearRecur(n - 1);
}
/* 平方阶 */
static void quadratic(int n)
{
static void quadratic(int n) {
// 矩阵占用 O(n^2) 空间
int[,] numMatrix = new int[n, n];
// 二维列表占用 O(n^2) 空间
List<List<int>> numList = new();
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
List<int> tmp = new();
for (int j = 0; j < n; j++)
{
for (int j = 0; j < n; j++) {
tmp.Add(0);
}
numList.Add(tmp);
@ -84,8 +72,7 @@ public class space_complexity
}
/* 平方阶（递归实现） */
static int quadraticRecur(int n)
{
static int quadraticRecur(int n) {
if (n <= 0) return 0;
int[] nums = new int[n];
Console.WriteLine("递归 n = " + n + " 中的 nums 长度 = " + nums.Length);
@ -93,8 +80,7 @@ public class space_complexity
}
/* 指数阶（建立满二叉树） */
static TreeNode? buildTree(int n)
{
static TreeNode? buildTree(int n) {
if (n == 0) return null;
TreeNode root = new TreeNode(0);
root.left = buildTree(n - 1);
@ -103,8 +89,7 @@ public class space_complexity
}
[Test]
public void Test()
{
public void Test() {
int n = 5;
// 常数阶
constant(n);

99
codes/csharp/chapter_computational_complexity/time_complexity.cs
View File

@ -8,52 +8,41 @@ using NUnit.Framework;
namespace hello_algo.chapter_computational_complexity;
public class time_complexity
{
void algorithm(int n)
{
public class time_complexity {
void algorithm(int n) {
int a = 1; // +0（技巧 1）
a = a + n; // +0（技巧 1）
// +n（技巧 2）
for (int i = 0; i < 5 * n + 1; i++)
{
for (int i = 0; i < 5 * n + 1; i++) {
Console.WriteLine(0);
}
// +n*n（技巧 3）
for (int i = 0; i < 2 * n; i++)
{
for (int j = 0; j < n + 1; j++)
{
for (int i = 0; i < 2 * n; i++) {
for (int j = 0; j < n + 1; j++) {
Console.WriteLine(0);
}
}
}
// 算法 A 时间复杂度：常数阶
void algorithm_A(int n)
{
void algorithm_A(int n) {
Console.WriteLine(0);
}
// 算法 B 时间复杂度：线性阶
void algorithm_B(int n)
{
for (int i = 0; i < n; i++)
{
void algorithm_B(int n) {
for (int i = 0; i < n; i++) {
Console.WriteLine(0);
}
}
// 算法 C 时间复杂度：常数阶
void algorithm_C(int n)
{
for (int i = 0; i < 1000000; i++)
{
void algorithm_C(int n) {
for (int i = 0; i < 1000000; i++) {
Console.WriteLine(0);
}
}
/* 常数阶 */
static int constant(int n)
{
static int constant(int n) {
int count = 0;
int size = 100000;
for (int i = 0; i < size; i++)
@ -62,8 +51,7 @@ public class time_complexity
}
/* 线性阶 */
static int linear(int n)
{
static int linear(int n) {
int count = 0;
for (int i = 0; i < n; i++)
count++;
@ -71,26 +59,21 @@ public class time_complexity
}
/* 线性阶（遍历数组） */
static int arrayTraversal(int[] nums)
{
static int arrayTraversal(int[] nums) {
int count = 0;
// 循环次数与数组长度成正比
foreach (int num in nums)
{
foreach (int num in nums) {
count++;
}
return count;
}
/* 平方阶 */
static int quadratic(int n)
{
static int quadratic(int n) {
int count = 0;
// 循环次数与数组长度成平方关系
for (int i = 0; i < n; i++)
{
for (int j = 0; j < n; j++)
{
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
count++;
}
}
@ -98,17 +81,13 @@ public class time_complexity
}
/* 平方阶（冒泡排序） */
static int bubbleSort(int[] nums)
{
static int bubbleSort(int[] nums) {
int count = 0; // 计数器
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (int i = nums.Length - 1; i > 0; i--)
{
for (int i = nums.Length - 1; i > 0; i--) {
// 内循环：冒泡操作
for (int j = 0; j < i; j++)
{
if (nums[j] > nums[j + 1])
{
for (int j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
int tmp = nums[j];
nums[j] = nums[j + 1];
@ -121,14 +100,11 @@ public class time_complexity
}
/* 指数阶（循环实现） */
static int exponential(int n)
{
static int exponential(int n) {
int count = 0, bas = 1;
// cell 每轮一分为二，形成数列 1, 2, 4, 8, ..., 2^(n-1)
for (int i = 0; i < n; i++)
{
for (int j = 0; j < bas; j++)
{
for (int i = 0; i < n; i++) {
for (int j = 0; j < bas; j++) {
count++;
}
bas *= 2;
@ -138,18 +114,15 @@ public class time_complexity
}
/* 指数阶（递归实现） */
static int expRecur(int n)
{
static int expRecur(int n) {
if (n == 1) return 1;
return expRecur(n - 1) + expRecur(n - 1) + 1;
}
/* 对数阶（循环实现） */
static int logarithmic(float n)
{
static int logarithmic(float n) {
int count = 0;
while (n > 1)
{
while (n > 1) {
n = n / 2;
count++;
}
@ -157,41 +130,35 @@ public class time_complexity
}
/* 对数阶（递归实现） */
static int logRecur(float n)
{
static int logRecur(float n) {
if (n <= 1) return 0;
return logRecur(n / 2) + 1;
}
/* 线性对数阶 */
static int linearLogRecur(float n)
{
static int linearLogRecur(float n) {
if (n <= 1) return 1;
int count = linearLogRecur(n / 2) +
linearLogRecur(n / 2);
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
count++;
}
return count;
}
/* 阶乘阶（递归实现） */
static int factorialRecur(int n)
{
static int factorialRecur(int n) {
if (n == 0) return 1;
int count = 0;
// 从 1 个分裂出 n 个
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
count += factorialRecur(n - 1);
}
return count;
}
[Test]
public void Test()
{
public void Test() {
// 可以修改 n 运行，体会一下各种复杂度的操作数量变化趋势
int n = 8;
Console.WriteLine("输入数据大小 n = " + n);

24
codes/csharp/chapter_computational_complexity/worst_best_time_complexity.cs
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@ -8,21 +8,17 @@ using NUnit.Framework;
namespace hello_algo.chapter_computational_complexity;
public class worst_best_time_complexity
{
public class worst_best_time_complexity {
/* 生成一个数组，元素为 { 1, 2, ..., n }，顺序被打乱 */
static int[] randomNumbers(int n)
{
static int[] randomNumbers(int n) {
int[] nums = new int[n];
// 生成数组 nums = { 1, 2, 3, ..., n }
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
nums[i] = i + 1;
}
// 随机打乱数组元素
for (int i = 0; i < nums.Length; i++)
{
for (int i = 0; i < nums.Length; i++) {
var index = new Random().Next(i, nums.Length);
var tmp = nums[i];
var ran = nums[index];
@ -33,10 +29,8 @@ public class worst_best_time_complexity
}
/* 查找数组 nums 中数字 1 所在索引 */
static int findOne(int[] nums)
{
for (int i = 0; i < nums.Length; i++)
{
static int findOne(int[] nums) {
for (int i = 0; i < nums.Length; i++) {
// 当元素 1 在数组头部时，达到最佳时间复杂度 O(1)
// 当元素 1 在数组尾部时，达到最差时间复杂度 O(n)
if (nums[i] == 1)
@ -48,10 +42,8 @@ public class worst_best_time_complexity
/* Driver Code */
[Test]
public void Test()
{
for (int i = 0; i < 10; i++)
{
public void Test() {
for (int i = 0; i < 10; i++) {
int n = 100;
int[] nums = randomNumbers(n);
int index = findOne(nums);

39
codes/csharp/chapter_graph/graph_adjacency_list.cs
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@ -10,18 +10,15 @@ using NUnit.Framework;
namespace hello_algo.chapter_graph;
/* 基于邻接表实现的无向图类 */
public class GraphAdjList
{
public class GraphAdjList {
// 邻接表，key: 顶点，value：该顶点的所有邻接顶点
public Dictionary<Vertex, List<Vertex>> adjList;
/* 构造函数 */
public GraphAdjList(Vertex[][] edges)
{
public GraphAdjList(Vertex[][] edges) {
this.adjList = new Dictionary<Vertex, List<Vertex>>();
// 添加所有顶点和边
foreach (Vertex[] edge in edges)
{
foreach (Vertex[] edge in edges) {
addVertex(edge[0]);
addVertex(edge[1]);
addEdge(edge[0], edge[1]);
@ -29,14 +26,12 @@ public class GraphAdjList
}
/* 获取顶点数量 */
public int size()
{
public int size() {
return adjList.Count;
}
/* 添加边 */
public void addEdge(Vertex vet1, Vertex vet2)
{
public void addEdge(Vertex vet1, Vertex vet2) {
if (!adjList.ContainsKey(vet1) || !adjList.ContainsKey(vet2) || vet1 == vet2)
throw new InvalidOperationException();
// 添加边 vet1 - vet2
@ -45,8 +40,7 @@ public class GraphAdjList
}
/* 删除边 */
public void removeEdge(Vertex vet1, Vertex vet2)
{
public void removeEdge(Vertex vet1, Vertex vet2) {
if (!adjList.ContainsKey(vet1) || !adjList.ContainsKey(vet2) || vet1 == vet2)
throw new InvalidOperationException();
// 删除边 vet1 - vet2
@ -55,8 +49,7 @@ public class GraphAdjList
}
/* 添加顶点 */
public void addVertex(Vertex vet)
{
public void addVertex(Vertex vet) {
if (adjList.ContainsKey(vet))
return;
// 在邻接表中添加一个新链表
@ -64,25 +57,21 @@ public class GraphAdjList
}
/* 删除顶点 */
public void removeVertex(Vertex vet)
{
public void removeVertex(Vertex vet) {
if (!adjList.ContainsKey(vet))
throw new InvalidOperationException();
// 在邻接表中删除顶点 vet 对应的链表
adjList.Remove(vet);
// 遍历其他顶点的链表，删除所有包含 vet 的边
foreach (List<Vertex> list in adjList.Values)
{
foreach (List<Vertex> list in adjList.Values) {
list.Remove(vet);
}
}
/* 打印邻接表 */
public void print()
{
public void print() {
Console.WriteLine("邻接表 =");
foreach (KeyValuePair<Vertex, List<Vertex>> entry in adjList)
{
foreach (KeyValuePair<Vertex, List<Vertex>> entry in adjList) {
List<int> tmp = new List<int>();
foreach (Vertex vertex in entry.Value)
tmp.Add(vertex.val);
@ -91,11 +80,9 @@ public class GraphAdjList
}
}
public class graph_adjacency_list
{
public class graph_adjacency_list {
[Test]
public void Test()
{
public void Test() {
/* 初始化无向图 */
Vertex[] v = Vertex.ValsToVets(new int[] { 1, 3, 2, 5, 4 });
Vertex[][] edges = new Vertex[][] { new Vertex[] { v[0], v[1] }, new Vertex[] { v[0], v[3] },

45
codes/csharp/chapter_graph/graph_adjacency_matrix.cs
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@ -10,58 +10,49 @@ using NUnit.Framework;
namespace hello_algo.chapter_graph;
/* 基于邻接矩阵实现的无向图类 */
class GraphAdjMat
{
class GraphAdjMat {
List<int> vertices; // 顶点列表，元素代表“顶点值”，索引代表“顶点索引”
List<List<int>> adjMat; // 邻接矩阵，行列索引对应“顶点索引”
/* 构造函数 */
public GraphAdjMat(int[] vertices, int[][] edges)
{
public GraphAdjMat(int[] vertices, int[][] edges) {
this.vertices = new List<int>();
this.adjMat = new List<List<int>>();
// 添加顶点
foreach (int val in vertices)
{
foreach (int val in vertices) {
addVertex(val);
}
// 添加边
// 请注意，edges 元素代表顶点索引，即对应 vertices 元素索引
foreach (int[] e in edges)
{
foreach (int[] e in edges) {
addEdge(e[0], e[1]);
}
}
/* 获取顶点数量 */
public int size()
{
public int size() {
return vertices.Count;
}
/* 添加顶点 */
public void addVertex(int val)
{
public void addVertex(int val) {
int n = size();
// 向顶点列表中添加新顶点的值
vertices.Add(val);
// 在邻接矩阵中添加一行
List<int> newRow = new List<int>(n);
for (int j = 0; j < n; j++)
{
for (int j = 0; j < n; j++) {
newRow.Add(0);
}
adjMat.Add(newRow);
// 在邻接矩阵中添加一列
foreach (List<int> row in adjMat)
{
foreach (List<int> row in adjMat) {
row.Add(0);
}
}
/* 删除顶点 */
public void removeVertex(int index)
{
public void removeVertex(int index) {
if (index >= size())
throw new IndexOutOfRangeException();
// 在顶点列表中移除索引 index 的顶点
@ -69,16 +60,14 @@ class GraphAdjMat
// 在邻接矩阵中删除索引 index 的行
adjMat.RemoveAt(index);
// 在邻接矩阵中删除索引 index 的列
foreach (List<int> row in adjMat)
{
foreach (List<int> row in adjMat) {
row.RemoveAt(index);
}
}
/* 添加边 */
// 参数 i, j 对应 vertices 元素索引
public void addEdge(int i, int j)
{
public void addEdge(int i, int j) {
// 索引越界与相等处理
if (i < 0 || j < 0 || i >= size() || j >= size() || i == j)
throw new IndexOutOfRangeException();
@ -89,8 +78,7 @@ class GraphAdjMat
/* 删除边 */
// 参数 i, j 对应 vertices 元素索引
public void removeEdge(int i, int j)
{
public void removeEdge(int i, int j) {
// 索引越界与相等处理
if (i < 0 || j < 0 || i >= size() || j >= size() || i == j)
throw new IndexOutOfRangeException();
@ -99,8 +87,7 @@ class GraphAdjMat
}
/* 打印邻接矩阵 */
public void print()
{
public void print() {
Console.Write("顶点列表 = ");
PrintUtil.PrintList(vertices);
Console.WriteLine("邻接矩阵 =");
@ -108,11 +95,9 @@ class GraphAdjMat
}
}
public class graph_adjacency_matrix
{
public class graph_adjacency_matrix {
[Test]
public void Test()
{
public void Test() {
/* 初始化无向图 */
// 请注意，edges 元素代表顶点索引，即对应 vertices 元素索引
int[] vertices = { 1, 3, 2, 5, 4 };

18
codes/csharp/chapter_graph/graph_bfs.cs
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@ -9,12 +9,10 @@ using NUnit.Framework;
namespace hello_algo.chapter_graph;
public class graph_bfs
{
public class graph_bfs {
/* 广度优先遍历 BFS */
// 使用邻接表来表示图，以便获取指定顶点的所有邻接顶点
public static List<Vertex> graphBFS(GraphAdjList graph, Vertex startVet)
{
public static List<Vertex> graphBFS(GraphAdjList graph, Vertex startVet) {
// 顶点遍历序列
List<Vertex> res = new List<Vertex>();
// 哈希表，用于记录已被访问过的顶点
@ -23,14 +21,11 @@ public class graph_bfs
Queue<Vertex> que = new Queue<Vertex>();
que.Enqueue(startVet);
// 以顶点 vet 为起点，循环直至访问完所有顶点
while (que.Count > 0)
{
while (que.Count > 0) {
Vertex vet = que.Dequeue(); // 队首顶点出队
res.Add(vet); // 记录访问顶点
foreach (Vertex adjVet in graph.adjList[vet])
{
if (visited.Contains(adjVet))
{
foreach (Vertex adjVet in graph.adjList[vet]) {
if (visited.Contains(adjVet)) {
continue; // 跳过已被访问过的顶点
}
que.Enqueue(adjVet); // 只入队未访问的顶点
@ -43,8 +38,7 @@ public class graph_bfs
}
[Test]
public void Test()
{
public void Test() {
/* 初始化无向图 */
Vertex[] v = Vertex.ValsToVets(new int[10] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 });
Vertex[][] edges = new Vertex[12][]

18
codes/csharp/chapter_graph/graph_dfs.cs
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@ -9,18 +9,14 @@ using NUnit.Framework;
namespace hello_algo.chapter_graph;
public class graph_dfs
{
public class graph_dfs {
/* 深度优先遍历 DFS 辅助函数 */
public void dfs(GraphAdjList graph, HashSet<Vertex> visited, List<Vertex> res, Vertex vet)
{
public void dfs(GraphAdjList graph, HashSet<Vertex> visited, List<Vertex> res, Vertex vet) {
res.Add(vet); // 记录访问顶点
visited.Add(vet); // 标记该顶点已被访问
// 遍历该顶点的所有邻接顶点
foreach (Vertex adjVet in graph.adjList[vet])
{
if (visited.Contains(adjVet))
{
foreach (Vertex adjVet in graph.adjList[vet]) {
if (visited.Contains(adjVet)) {
continue; // 跳过已被访问过的顶点
}
// 递归访问邻接顶点
@ -30,8 +26,7 @@ public class graph_dfs
/* 深度优先遍历 DFS */
// 使用邻接表来表示图，以便获取指定顶点的所有邻接顶点
public List<Vertex> graphDFS(GraphAdjList graph, Vertex startVet)
{
public List<Vertex> graphDFS(GraphAdjList graph, Vertex startVet) {
// 顶点遍历序列
List<Vertex> res = new List<Vertex>();
// 哈希表，用于记录已被访问过的顶点
@ -41,8 +36,7 @@ public class graph_dfs
}
[Test]
public void Test()
{
public void Test() {
/* 初始化无向图 */
Vertex[] v = Vertex.ValsToVets(new int[7] { 0, 1, 2, 3, 4, 5, 6 });
Vertex[][] edges = new Vertex[6][]

66
codes/csharp/chapter_hashing/array_hash_map.cs
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@ -9,41 +9,34 @@ using NUnit.Framework;
namespace hello_algo.chapter_hashing;
/* 键值对 int->string */
class Entry
{
class Entry {
public int key;
public string val;
public Entry(int key, string val)
{
public Entry(int key, string val) {
this.key = key;
this.val = val;
}
}
/* 基于数组简易实现的哈希表 */
class ArrayHashMap
{
class ArrayHashMap {
private List<Entry?> buckets;
public ArrayHashMap()
{
public ArrayHashMap() {
// 初始化数组，包含 100 个桶
buckets = new();
for (int i = 0; i < 100; i++)
{
for (int i = 0; i < 100; i++) {
buckets.Add(null);
}
}
/* 哈希函数 */
private int hashFunc(int key)
{
private int hashFunc(int key) {
int index = key % 100;
return index;
}
/* 查询操作 */
public string? get(int key)
{
public string? get(int key) {
int index = hashFunc(key);
Entry? pair = buckets[index];
if (pair == null) return null;
@ -51,27 +44,23 @@ class ArrayHashMap
}
/* 添加操作 */
public void put(int key, string val)
{
public void put(int key, string val) {
Entry pair = new Entry(key, val);
int index = hashFunc(key);
buckets[index] = pair;
}
/* 删除操作 */
public void remove(int key)
{
public void remove(int key) {
int index = hashFunc(key);
// 置为 null ，代表删除
buckets[index] = null;
}
/* 获取所有键值对 */
public List<Entry> entrySet()
{
public List<Entry> entrySet() {
List<Entry> entrySet = new();
foreach (Entry? pair in buckets)
{
foreach (Entry? pair in buckets) {
if (pair != null)
entrySet.Add(pair);
}
@ -79,11 +68,9 @@ class ArrayHashMap
}
/* 获取所有键 */
public List<int> keySet()
{
public List<int> keySet() {
List<int> keySet = new();
foreach (Entry? pair in buckets)
{
foreach (Entry? pair in buckets) {
if (pair != null)
keySet.Add(pair.key);
}
@ -91,11 +78,9 @@ class ArrayHashMap
}
/* 获取所有值 */
public List<string> valueSet()
{
public List<string> valueSet() {
List<string> valueSet = new();
foreach (Entry? pair in buckets)
{
foreach (Entry? pair in buckets) {
if (pair != null)
valueSet.Add(pair.val);
}
@ -103,21 +88,17 @@ class ArrayHashMap
}
/* 打印哈希表 */
public void print()
{
foreach (Entry kv in entrySet())
{
public void print() {
foreach (Entry kv in entrySet()) {
Console.WriteLine(kv.key + " -> " + kv.val);
}
}
}
public class array_hash_map
{
public class array_hash_map {
[Test]
public void Test()
{
public void Test() {
/* 初始化哈希表 */
ArrayHashMap map = new ArrayHashMap();
@ -144,18 +125,15 @@ public class array_hash_map
/* 遍历哈希表 */
Console.WriteLine("\n遍历键值对 Key->Value");
foreach (Entry kv in map.entrySet())
{
foreach (Entry kv in map.entrySet()) {
Console.WriteLine(kv.key + " -> " + kv.val);
}
Console.WriteLine("\n单独遍历键 Key");
foreach (int key in map.keySet())
{
foreach (int key in map.keySet()) {
Console.WriteLine(key);
}
Console.WriteLine("\n单独遍历值 Value");
foreach (string val in map.valueSet())
{
foreach (string val in map.valueSet()) {
Console.WriteLine(val);
}
}

15
codes/csharp/chapter_hashing/hash_map.cs
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@ -10,11 +10,9 @@ using NUnit.Framework;
namespace hello_algo.chapter_hashing;
public class hash_map
{
public class hash_map {
[Test]
public void Test()
{
public void Test() {
/* 初始化哈希表 */
Dictionary<int, string> map = new();
@ -41,18 +39,15 @@ public class hash_map
/* 遍历哈希表 */
Console.WriteLine("\n遍历键值对 Key->Value");
foreach (var kv in map)
{
foreach (var kv in map) {
Console.WriteLine(kv.Key + " -> " + kv.Value);
}
Console.WriteLine("\n单独遍历键 Key");
foreach (int key in map.Keys)
{
foreach (int key in map.Keys) {
Console.WriteLine(key);
}
Console.WriteLine("\n单独遍历值 Value");
foreach (string val in map.Values)
{
foreach (string val in map.Values) {
Console.WriteLine(val);
}
}

12
codes/csharp/chapter_heap/heap.cs
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@ -9,24 +9,20 @@ using NUnit.Framework;
namespace hello_algo.chapter_heap;
public class heap
{
public void testPush(PriorityQueue<int, int> heap, int val)
{
public class heap {
public void testPush(PriorityQueue<int, int> heap, int val) {
heap.Enqueue(val, val); // 元素入堆
Console.WriteLine($"\n元素 {val} 入堆后\n");
PrintUtil.PrintHeap(heap);
}
public void testPop(PriorityQueue<int, int> heap)
{
public void testPop(PriorityQueue<int, int> heap) {
int val = heap.Dequeue(); // 堆顶元素出堆
Console.WriteLine($"\n堆顶元素 {val} 出堆后\n");
PrintUtil.PrintHeap(heap);
}
[Test]
public void Test()
{
public void Test() {
/* 初始化堆 */
// 初始化小顶堆
PriorityQueue<int, int> minHeap = new PriorityQueue<int, int>();

60
codes/csharp/chapter_heap/my_heap.cs
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@ -10,57 +10,48 @@ using NUnit.Framework;
namespace hello_algo.chapter_heap;
/* 大顶堆 */
class MaxHeap
{
class MaxHeap {
// 使用列表而非数组，这样无需考虑扩容问题
private readonly List<int> maxHeap;
/* 构造函数，建立空堆 */
public MaxHeap()
{
public MaxHeap() {
maxHeap = new List<int>();
}
/* 构造函数，根据输入列表建堆 */
public MaxHeap(IEnumerable<int> nums)
{
public MaxHeap(IEnumerable<int> nums) {
// 将列表元素原封不动添加进堆
maxHeap = new List<int>(nums);
// 堆化除叶节点以外的其他所有节点
var size = parent(this.size() - 1);
for (int i = size; i >= 0; i--)
{
for (int i = size; i >= 0; i--) {
siftDown(i);
}
}
/* 获取左子节点索引 */
int left(int i)
{
int left(int i) {
return 2 * i + 1;
}
/* 获取右子节点索引 */
int right(int i)
{
int right(int i) {
return 2 * i + 2;
}
/* 获取父节点索引 */
int parent(int i)
{
int parent(int i) {
return (i - 1) / 2; // 向下整除
}
/* 访问堆顶元素 */
public int peek()
{
public int peek() {
return maxHeap[0];
}
/* 元素入堆 */
public void push(int val)
{
public void push(int val) {
// 添加节点
maxHeap.Add(val);
// 从底至顶堆化
@ -68,22 +59,18 @@ class MaxHeap
}
/* 获取堆大小 */
public int size()
{
public int size() {
return maxHeap.Count;
}
/* 判断堆是否为空 */
public bool isEmpty()
{
public bool isEmpty() {
return size() == 0;
}
/* 从节点 i 开始，从底至顶堆化 */
void siftUp(int i)
{
while (true)
{
void siftUp(int i) {
while (true) {
// 获取节点 i 的父节点
int p = parent(i);
// 若“越过根节点”或“节点无需修复”，则结束堆化
@ -97,8 +84,7 @@ class MaxHeap
}
/* 元素出堆 */
public int pop()
{
public int pop() {
// 判空处理
if (isEmpty())
throw new IndexOutOfRangeException();
@ -114,10 +100,8 @@ class MaxHeap
}
/* 从节点 i 开始，从顶至底堆化 */
void siftDown(int i)
{
while (true)
{
void siftDown(int i) {
while (true) {
// 判断节点 i, l, r 中值最大的节点，记为 ma
int l = left(i), r = right(i), ma = i;
if (l < size() && maxHeap[l] > maxHeap[ma])
@ -134,24 +118,20 @@ class MaxHeap
}
/* 交换元素 */
void swap(int i, int p)
{
void swap(int i, int p) {
(maxHeap[i], maxHeap[p]) = (maxHeap[p], maxHeap[i]);
}
/* 打印堆（二叉树） */
public void print()
{
public void print() {
var queue = new Queue<int>(maxHeap);
PrintUtil.PrintHeap(queue);
}
}
public class my_heap
{
public class my_heap {
[Test]
public void Test()
{
public void Test() {
/* 初始化大顶堆 */
MaxHeap maxHeap = new MaxHeap(new int[] { 9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2 });
Console.WriteLine("\n输入列表并建堆后");

18
codes/csharp/chapter_searching/hashing_search.cs
View File

@ -9,19 +9,16 @@ using NUnit.Framework;
namespace hello_algo.chapter_searching;
public class hashing_search
{
public class hashing_search {
/* 哈希查找（数组） */
static int hashingSearchArray(Dictionary<int, int> map, int target)
{
static int hashingSearchArray(Dictionary<int, int> map, int target) {
// 哈希表的 key: 目标元素，value: 索引
// 若哈希表中无此 key ，返回 -1
return map.GetValueOrDefault(target, -1);
}
/* 哈希查找（链表） */
static ListNode? hashingSearchLinkedList(Dictionary<int, ListNode> map, int target)
{
static ListNode? hashingSearchLinkedList(Dictionary<int, ListNode> map, int target) {
// 哈希表的 key: 目标节点值，value: 节点对象
// 若哈希表中无此 key ，返回 null
@ -29,16 +26,14 @@ public class hashing_search
}
[Test]
public void Test()
{
public void Test() {
int target = 3;
/* 哈希查找（数组） */
int[] nums = { 1, 5, 3, 2, 4, 7, 5, 9, 10, 8 };
// 初始化哈希表
Dictionary<int, int> map = new();
for (int i = 0; i < nums.Length; i++)
{
for (int i = 0; i < nums.Length; i++) {
map[nums[i]] = i; // key: 元素，value: 索引
}
int index = hashingSearchArray(map, target);
@ -48,8 +43,7 @@ public class hashing_search
ListNode? head = ListNode.ArrToLinkedList(nums);
// 初始化哈希表
Dictionary<int, ListNode> map1 = new();
while (head != null)
{
while (head != null) {
map1[head.val] = head; // key: 节点值，value: 节点
head = head.next;
}

24
codes/csharp/chapter_searching/leetcode_two_sum.cs
View File

@ -8,17 +8,13 @@ using NUnit.Framework;
namespace hello_algo.chapter_searching;
public class leetcode_two_sum
{
public class leetcode_two_sum {
/* 方法一：暴力枚举 */
public static int[] twoSumBruteForce(int[] nums, int target)
{
public static int[] twoSumBruteForce(int[] nums, int target) {
int size = nums.Length;
// 两层循环，时间复杂度 O(n^2)
for (int i = 0; i < size - 1; i++)
{
for (int j = i + 1; j < size; j++)
{
for (int i = 0; i < size - 1; i++) {
for (int j = i + 1; j < size; j++) {
if (nums[i] + nums[j] == target)
return new int[] { i, j };
}
@ -27,16 +23,13 @@ public class leetcode_two_sum
}
/* 方法二：辅助哈希表 */
public static int[] twoSumHashTable(int[] nums, int target)
{
public static int[] twoSumHashTable(int[] nums, int target) {
int size = nums.Length;
// 辅助哈希表，空间复杂度 O(n)
Dictionary<int, int> dic = new();
// 单层循环，时间复杂度 O(n)
for (int i = 0; i < size; i++)
{
if (dic.ContainsKey(target - nums[i]))
{
for (int i = 0; i < size; i++) {
if (dic.ContainsKey(target - nums[i])) {
return new int[] { dic[target - nums[i]], i };
}
dic.Add(nums[i], i);
@ -45,8 +38,7 @@ public class leetcode_two_sum
}
[Test]
public void Test()
{
public void Test() {
// ======= Test Case =======
int[] nums = { 2, 7, 11, 15 };
int target = 9;

18
codes/csharp/chapter_searching/linear_search.cs
View File

@ -9,14 +9,11 @@ using NUnit.Framework;
namespace hello_algo.chapter_searching;
public class linear_search
{
public class linear_search {
/* 线性查找（数组） */
static int linearSearchArray(int[] nums, int target)
{
static int linearSearchArray(int[] nums, int target) {
// 遍历数组
for (int i = 0; i < nums.Length; i++)
{
for (int i = 0; i < nums.Length; i++) {
// 找到目标元素，返回其索引
if (nums[i] == target)
return i;
@ -26,11 +23,9 @@ public class linear_search
}
/* 线性查找（链表） */
static ListNode? linearSearchLinkedList(ListNode head, int target)
{
static ListNode? linearSearchLinkedList(ListNode head, int target) {
// 遍历链表
while (head != null)
{
while (head != null) {
// 找到目标节点，返回之
if (head.val == target)
return head;
@ -41,8 +36,7 @@ public class linear_search
}
[Test]
public void Test()
{
public void Test() {
int target = 3;
/* 在数组中执行线性查找 */

30
codes/csharp/chapter_sorting/bubble_sort.cs
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@ -8,19 +8,14 @@ using NUnit.Framework;
namespace hello_algo.chapter_sorting;
public class bubble_sort
{
public class bubble_sort {
/* 冒泡排序 */
static void bubbleSort(int[] nums)
{
static void bubbleSort(int[] nums) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (int i = nums.Length - 1; i > 0; i--)
{
for (int i = nums.Length - 1; i > 0; i--) {
// 内循环：冒泡操作
for (int j = 0; j < i; j++)
{
if (nums[j] > nums[j + 1])
{
for (int j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
int tmp = nums[j];
nums[j] = nums[j + 1];
@ -31,17 +26,13 @@ public class bubble_sort
}
/* 冒泡排序（标志优化）*/
static void bubbleSortWithFlag(int[] nums)
{
static void bubbleSortWithFlag(int[] nums) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (int i = nums.Length - 1; i > 0; i--)
{
for (int i = nums.Length - 1; i > 0; i--) {
bool flag = false; // 初始化标志位
// 内循环：冒泡操作
for (int j = 0; j < i; j++)
{
if (nums[j] > nums[j + 1])
{
for (int j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
int tmp = nums[j];
nums[j] = nums[j + 1];
@ -54,8 +45,7 @@ public class bubble_sort
}
[Test]
public void Test()
{
public void Test() {
int[] nums = { 4, 1, 3, 1, 5, 2 };
bubbleSort(nums);
Console.WriteLine("冒泡排序完成后 nums = " + string.Join(",", nums));

24
codes/csharp/chapter_sorting/bucket_sort.cs
View File

@ -8,46 +8,38 @@ using NUnit.Framework;
namespace hello_algo.chapter_sorting;
public class bucket_sort
{
public class bucket_sort {
/* 桶排序 */
public static void bucketSort(float[] nums)
{
public static void bucketSort(float[] nums) {
// 初始化 k = n/2 个桶，预期向每个桶分配 2 个元素
int k = nums.Length / 2;
List<List<float>> buckets = new List<List<float>>();
for (int i = 0; i < k; i++)
{
for (int i = 0; i < k; i++) {
buckets.Add(new List<float>());
}
// 1. 将数组元素分配到各个桶中
foreach (float num in nums)
{
foreach (float num in nums) {
// 输入数据范围 [0, 1)，使用 num * k 映射到索引范围 [0, k-1]
int i = (int)num * k;
// 将 num 添加进桶 i
buckets[i].Add(num);
}
// 2. 对各个桶执行排序
foreach (List<float> bucket in buckets)
{
foreach (List<float> bucket in buckets) {
// 使用内置排序函数，也可以替换成其他排序算法
bucket.Sort();
}
// 3. 遍历桶合并结果
int j = 0;
foreach (List<float> bucket in buckets)
{
foreach (float num in bucket)
{
foreach (List<float> bucket in buckets) {
foreach (float num in bucket) {
nums[j++] = num;
}
}
}
[Test]
public void Test()
{
public void Test() {
// 设输入数据为浮点数，范围为 [0, 1)
float[] nums = { 0.49f, 0.96f, 0.82f, 0.09f, 0.57f, 0.43f, 0.91f, 0.75f, 0.15f, 0.37f };
bucketSort(nums);

39
codes/csharp/chapter_sorting/counting_sort.cs
View File

@ -8,31 +8,25 @@ using NUnit.Framework;
namespace hello_algo.chapter_sorting;
public class counting_sort
{
public class counting_sort {
/* 计数排序 */
// 简单实现，无法用于排序对象
public static void countingSortNaive(int[] nums)
{
public static void countingSortNaive(int[] nums) {
// 1. 统计数组最大元素 m
int m = 0;
foreach (int num in nums)
{
foreach (int num in nums) {
m = Math.Max(m, num);
}
// 2. 统计各数字的出现次数
// counter[num] 代表 num 的出现次数
int[] counter = new int[m + 1];
foreach (int num in nums)
{
foreach (int num in nums) {
counter[num]++;
}
// 3. 遍历 counter ，将各元素填入原数组 nums
int i = 0;
for (int num = 0; num < m + 1; num++)
{
for (int j = 0; j < counter[num]; j++, i++)
{
for (int num = 0; num < m + 1; num++) {
for (int j = 0; j < counter[num]; j++, i++) {
nums[i] = num;
}
}
@ -40,47 +34,40 @@ public class counting_sort
/* 计数排序 */
// 完整实现，可排序对象，并且是稳定排序
static void countingSort(int[] nums)
{
static void countingSort(int[] nums) {
// 1. 统计数组最大元素 m
int m = 0;
foreach (int num in nums)
{
foreach (int num in nums) {
m = Math.Max(m, num);
}
// 2. 统计各数字的出现次数
// counter[num] 代表 num 的出现次数
int[] counter = new int[m + 1];
foreach (int num in nums)
{
foreach (int num in nums) {
counter[num]++;
}
// 3. 求 counter 的前缀和，将“出现次数”转换为“尾索引”
// 即 counter[num]-1 是 num 在 res 中最后一次出现的索引
for (int i = 0; i < m; i++)
{
for (int i = 0; i < m; i++) {
counter[i + 1] += counter[i];
}
// 4. 倒序遍历 nums ，将各元素填入结果数组 res
// 初始化数组 res 用于记录结果
int n = nums.Length;
int[] res = new int[n];
for (int i = n - 1; i >= 0; i--)
{
for (int i = n - 1; i >= 0; i--) {
int num = nums[i];
res[counter[num] - 1] = num; // 将 num 放置到对应索引处
counter[num]--; // 令前缀和自减 1 ，得到下次放置 num 的索引
}
// 使用结果数组 res 覆盖原数组 nums
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
nums[i] = res[i];
}
}
[Test]
public void Test()
{
public void Test() {
int[] nums = { 1, 0, 1, 2, 0, 4, 0, 2, 2, 4 };
countingSortNaive(nums);
Console.WriteLine("计数排序（无法排序对象）完成后 nums = " + string.Join(" ", nums));

15
codes/csharp/chapter_sorting/insertion_sort.cs
View File

@ -8,18 +8,14 @@ using NUnit.Framework;
namespace hello_algo.chapter_sorting;
public class insertion_sort
{
public class insertion_sort {
/* 插入排序 */
static void insertionSort(int[] nums)
{
static void insertionSort(int[] nums) {
// 外循环：base = nums[1], nums[2], ..., nums[n-1]
for (int i = 1; i < nums.Length; i++)
{
for (int i = 1; i < nums.Length; i++) {
int bas = nums[i], j = i - 1;
// 内循环：将 base 插入到左边的正确位置
while (j >= 0 && nums[j] > bas)
{
while (j >= 0 && nums[j] > bas) {
nums[j + 1] = nums[j]; // 1. 将 nums[j] 向右移动一位
j--;
}
@ -28,8 +24,7 @@ public class insertion_sort
}
[Test]
public void Test()
{
public void Test() {
int[] nums = { 4, 1, 3, 1, 5, 2 };
insertionSort(nums);
Console.WriteLine("插入排序完成后 nums = " + string.Join(",", nums));

15
codes/csharp/chapter_sorting/merge_sort.cs
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@ -8,13 +8,11 @@ using NUnit.Framework;
namespace hello_algo.chapter_sorting;
public class merge_sort
{
public class merge_sort {
/* 合并左子数组和右子数组 */
// 左子数组区间 [left, mid]
// 右子数组区间 [mid + 1, right]
static void merge(int[] nums, int left, int mid, int right)
{
static void merge(int[] nums, int left, int mid, int right) {
// 初始化辅助数组
int[] tmp = nums[left..(right + 1)];
// 左子数组的起始索引和结束索引
@ -24,8 +22,7 @@ public class merge_sort
// i, j 分别指向左子数组、右子数组的首元素
int i = leftStart, j = rightStart;
// 通过覆盖原数组 nums 来合并左子数组和右子数组
for (int k = left; k <= right; k++)
{
for (int k = left; k <= right; k++) {
// 若“左子数组已全部合并完”，则选取右子数组元素，并且 j++
if (i > leftEnd)
nums[k] = tmp[j++];
@ -39,8 +36,7 @@ public class merge_sort
}
/* 归并排序 */
static void mergeSort(int[] nums, int left, int right)
{
static void mergeSort(int[] nums, int left, int right) {
// 终止条件
if (left >= right) return; // 当子数组长度为 1 时终止递归
// 划分阶段
@ -52,8 +48,7 @@ public class merge_sort
}
[Test]
public void Test()
{
public void Test() {
/* 归并排序 */
int[] nums = { 7, 3, 2, 6, 0, 1, 5, 4 };
mergeSort(nums, 0, nums.Length - 1);

64
codes/csharp/chapter_sorting/quick_sort.cs
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@ -8,23 +8,19 @@ using NUnit.Framework;
namespace hello_algo.chapter_sorting;
class QuickSort
{
class QuickSort {
/* 元素交换 */
static void swap(int[] nums, int i, int j)
{
static void swap(int[] nums, int i, int j) {
int tmp = nums[i];
nums[i] = nums[j];
nums[j] = tmp;
}
/* 哨兵划分 */
static int partition(int[] nums, int left, int right)
{
static int partition(int[] nums, int left, int right) {
// 以 nums[left] 作为基准数
int i = left, j = right;
while (i < j)
{
while (i < j) {
while (i < j && nums[j] >= nums[left])
j--; // 从右向左找首个小于基准数的元素
while (i < j && nums[i] <= nums[left])
@ -36,8 +32,7 @@ class QuickSort
}
/* 快速排序 */
public static void quickSort(int[] nums, int left, int right)
{
public static void quickSort(int[] nums, int left, int right) {
// 子数组长度为 1 时终止递归
if (left >= right)
return;
@ -50,19 +45,16 @@ class QuickSort
}
/* 快速排序类（中位基准数优化） */
class QuickSortMedian
{
class QuickSortMedian {
/* 元素交换 */
static void swap(int[] nums, int i, int j)
{
static void swap(int[] nums, int i, int j) {
int tmp = nums[i];
nums[i] = nums[j];
nums[j] = tmp;
}
/* 选取三个元素的中位数 */
static int medianThree(int[] nums, int left, int mid, int right)
{
static int medianThree(int[] nums, int left, int mid, int right) {
// 此处使用异或运算来简化代码
// 异或规则为 0 ^ 0 = 1 ^ 1 = 0, 0 ^ 1 = 1 ^ 0 = 1
if ((nums[left] < nums[mid]) ^ (nums[left] < nums[right]))
@ -74,16 +66,14 @@ class QuickSortMedian
}
/* 哨兵划分（三数取中值） */
static int partition(int[] nums, int left, int right)
{
static int partition(int[] nums, int left, int right) {
// 选取三个候选元素的中位数
int med = medianThree(nums, left, (left + right) / 2, right);
// 将中位数交换至数组最左端
swap(nums, left, med);
// 以 nums[left] 作为基准数
int i = left, j = right;
while (i < j)
{
while (i < j) {
while (i < j && nums[j] >= nums[left])
j--; // 从右向左找首个小于基准数的元素
while (i < j && nums[i] <= nums[left])
@ -95,8 +85,7 @@ class QuickSortMedian
}
/* 快速排序 */
public static void quickSort(int[] nums, int left, int right)
{
public static void quickSort(int[] nums, int left, int right) {
// 子数组长度为 1 时终止递归
if (left >= right)
return;
@ -109,23 +98,19 @@ class QuickSortMedian
}
/* 快速排序类（尾递归优化） */
class QuickSortTailCall
{
class QuickSortTailCall {
/* 元素交换 */
static void swap(int[] nums, int i, int j)
{
static void swap(int[] nums, int i, int j) {
int tmp = nums[i];
nums[i] = nums[j];
nums[j] = tmp;
}
/* 哨兵划分 */
static int partition(int[] nums, int left, int right)
{
static int partition(int[] nums, int left, int right) {
// 以 nums[left] 作为基准数
int i = left, j = right;
while (i < j)
{
while (i < j) {
while (i < j && nums[j] >= nums[left])
j--; // 从右向左找首个小于基准数的元素
while (i < j && nums[i] <= nums[left])
@ -137,21 +122,16 @@ class QuickSortTailCall
}
/* 快速排序（尾递归优化） */
public static void quickSort(int[] nums, int left, int right)
{
public static void quickSort(int[] nums, int left, int right) {
// 子数组长度为 1 时终止
while (left < right)
{
while (left < right) {
// 哨兵划分操作
int pivot = partition(nums, left, right);
// 对两个子数组中较短的那个执行快排
if (pivot - left < right - pivot)
{
if (pivot - left < right - pivot) {
quickSort(nums, left, pivot - 1); // 递归排序左子数组
left = pivot + 1; // 剩余待排序区间为 [pivot + 1, right]
}
else
{
} else {
quickSort(nums, pivot + 1, right); // 递归排序右子数组
right = pivot - 1; // 剩余待排序区间为 [left, pivot - 1]
}
@ -159,11 +139,9 @@ class QuickSortTailCall
}
}
public class quick_sort
{
public class quick_sort {
[Test]
public void Test()
{
public void Test() {
/* 快速排序 */
int[] nums = { 2, 4, 1, 0, 3, 5 };
QuickSort.quickSort(nums, 0, nums.Length - 1);

33
codes/csharp/chapter_sorting/radix_sort.cs
View File

@ -8,60 +8,50 @@ using NUnit.Framework;
namespace hello_algo.chapter_sorting;
public class radix_sort
{
public class radix_sort {
/* 获取元素 num 的第 k 位，其中 exp = 10^(k-1) */
static int digit(int num, int exp)
{
static int digit(int num, int exp) {
// 传入 exp 而非 k 可以避免在此重复执行昂贵的次方计算
return (num / exp) % 10;
}
/* 计数排序（根据 nums 第 k 位排序） */
static void countingSortDigit(int[] nums, int exp)
{
static void countingSortDigit(int[] nums, int exp) {
// 十进制的位范围为 0~9 ，因此需要长度为 10 的桶
int[] counter = new int[10];
int n = nums.Length;
// 统计 0~9 各数字的出现次数
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
int d = digit(nums[i], exp); // 获取 nums[i] 第 k 位，记为 d
counter[d]++; // 统计数字 d 的出现次数
}
// 求前缀和，将“出现个数”转换为“数组索引”
for (int i = 1; i < 10; i++)
{
for (int i = 1; i < 10; i++) {
counter[i] += counter[i - 1];
}
// 倒序遍历，根据桶内统计结果，将各元素填入 res
int[] res = new int[n];
for (int i = n - 1; i >= 0; i--)
{
for (int i = n - 1; i >= 0; i--) {
int d = digit(nums[i], exp);
int j = counter[d] - 1; // 获取 d 在数组中的索引 j
res[j] = nums[i]; // 将当前元素填入索引 j
counter[d]--; // 将 d 的数量减 1
}
// 使用结果覆盖原数组 nums
for (int i = 0; i < n; i++)
{
for (int i = 0; i < n; i++) {
nums[i] = res[i];
}
}
/* 基数排序 */
static void radixSort(int[] nums)
{
static void radixSort(int[] nums) {
// 获取数组的最大元素，用于判断最大位数
int m = int.MinValue;
foreach (int num in nums)
{
foreach (int num in nums) {
if (num > m) m = num;
}
// 按照从低位到高位的顺序遍历
for (int exp = 1; exp <= m; exp *= 10)
{
for (int exp = 1; exp <= m; exp *= 10) {
// 对数组元素的第 k 位执行计数排序
// k = 1 -> exp = 1
// k = 2 -> exp = 10
@ -71,8 +61,7 @@ public class radix_sort
}
[Test]
public void Test()
{
public void Test() {
// 基数排序
int[] nums = { 10546151, 35663510, 42865989, 34862445, 81883077,
88906420, 72429244, 30524779, 82060337, 63832996 };

63
codes/csharp/chapter_stack_and_queue/array_deque.cs
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@ -6,43 +6,36 @@
using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue
{
namespace hello_algo.chapter_stack_and_queue {
/* 基于环形数组实现的双向队列 */
public class ArrayDeque
{
public class ArrayDeque {
private readonly int[] nums; // 用于存储双向队列元素的数组
private int front; // 队首指针，指向队首元素
private int queSize; // 双向队列长度
/* 构造方法 */
public ArrayDeque(int capacity)
{
public ArrayDeque(int capacity) {
this.nums = new int[capacity];
front = queSize = 0;
}
/* 获取双向队列的容量 */
public int capacity()
{
public int capacity() {
return nums.Length;
}
/* 获取双向队列的长度 */
public int size()
{
public int size() {
return queSize;
}
/* 判断双向队列是否为空 */
public bool isEmpty()
{
public bool isEmpty() {
return queSize == 0;
}
/* 计算环形数组索引 */
private int index(int i)
{
private int index(int i) {
// 通过取余操作实现数组首尾相连
// 当 i 越过数组尾部后，回到头部
// 当 i 越过数组头部后，回到尾部
@ -50,10 +43,8 @@ namespace hello_algo.chapter_stack_and_queue
}
/* 队首入队 */
public void pushFirst(int num)
{
if (queSize == capacity())
{
public void pushFirst(int num) {
if (queSize == capacity()) {
Console.WriteLine("双向队列已满");
return;
}
@ -66,10 +57,8 @@ namespace hello_algo.chapter_stack_and_queue
}
/* 队尾入队 */
public void pushLast(int num)
{
if (queSize == capacity())
{
public void pushLast(int num) {
if (queSize == capacity()) {
Console.WriteLine("双向队列已满");
return;
}
@ -81,8 +70,7 @@ namespace hello_algo.chapter_stack_and_queue
}
/* 队首出队 */
public int popFirst()
{
public int popFirst() {
int num = peekFirst();
// 队首指针向后移动一位
front = index(front + 1);
@ -91,28 +79,23 @@ namespace hello_algo.chapter_stack_and_queue
}
/* 队尾出队 */
public int popLast()
{
public int popLast() {
int num = peekLast();
queSize--;
return num;
}
/* 访问队首元素 */
public int peekFirst()
{
if (isEmpty())
{
public int peekFirst() {
if (isEmpty()) {
throw new InvalidOperationException();
}
return nums[front];
}
/* 访问队尾元素 */
public int peekLast()
{
if (isEmpty())
{
public int peekLast() {
if (isEmpty()) {
throw new InvalidOperationException();
}
// 计算尾元素索引
@ -121,23 +104,19 @@ namespace hello_algo.chapter_stack_and_queue
}
/* 返回数组用于打印 */
public int[] toArray()
{
public int[] toArray() {
// 仅转换有效长度范围内的列表元素
int[] res = new int[queSize];
for (int i = 0, j = front; i < queSize; i++, j++)
{
for (int i = 0, j = front; i < queSize; i++, j++) {
res[i] = nums[index(j)];
}
return res;
}
}
public class array_deque
{
public class array_deque {
[Test]
public void Test()
{
public void Test() {
/* 初始化双向队列 */
ArrayDeque deque = new ArrayDeque(10);
deque.pushLast(3);

42
codes/csharp/chapter_stack_and_queue/array_queue.cs
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@ -9,41 +9,34 @@ using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue;
/* 基于环形数组实现的队列 */
class ArrayQueue
{
class ArrayQueue {
private int[] nums; // 用于存储队列元素的数组
private int front; // 队首指针，指向队首元素
private int queSize; // 队列长度
public ArrayQueue(int capacity)
{
public ArrayQueue(int capacity) {
nums = new int[capacity];
front = queSize = 0;
}
/* 获取队列的容量 */
public int capacity()
{
public int capacity() {
return nums.Length;
}
/* 获取队列的长度 */
public int size()
{
public int size() {
return queSize;
}
/* 判断队列是否为空 */
public bool isEmpty()
{
public bool isEmpty() {
return queSize == 0;
}
/* 入队 */
public void push(int num)
{
if (queSize == capacity())
{
public void push(int num) {
if (queSize == capacity()) {
Console.WriteLine("队列已满");
return;
}
@ -56,8 +49,7 @@ class ArrayQueue
}
/* 出队 */
public int pop()
{
public int pop() {
int num = peek();
// 队首指针向后移动一位，若越过尾部则返回到数组头部
front = (front + 1) % capacity();
@ -66,31 +58,26 @@ class ArrayQueue
}
/* 访问队首元素 */
public int peek()
{
public int peek() {
if (isEmpty())
throw new Exception();
return nums[front];
}
/* 返回数组 */
public int[] toArray()
{
public int[] toArray() {
// 仅转换有效长度范围内的列表元素
int[] res = new int[queSize];
for (int i = 0, j = front; i < queSize; i++, j++)
{
for (int i = 0, j = front; i < queSize; i++, j++) {
res[i] = nums[j % this.capacity()];
}
return res;
}
}
public class array_queue
{
public class array_queue {
[Test]
public void Test()
{
public void Test() {
/* 初始化队列 */
int capacity = 10;
ArrayQueue queue = new ArrayQueue(capacity);
@ -120,8 +107,7 @@ public class array_queue
Console.WriteLine("队列是否为空 = " + isEmpty);
/* 测试环形数组 */
for (int i = 0; i < 10; i++)
{
for (int i = 0; i < 10; i++) {
queue.push(i);
queue.pop();
Console.WriteLine("第 " + i + " 轮入队 + 出队后 queue = " + string.Join(",", queue.toArray()));

30
codes/csharp/chapter_stack_and_queue/array_stack.cs
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@ -9,36 +9,30 @@ using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue;
/* 基于数组实现的栈 */
class ArrayStack
{
class ArrayStack {
private List<int> stack;
public ArrayStack()
{
public ArrayStack() {
// 初始化列表（动态数组）
stack = new();
}
/* 获取栈的长度 */
public int size()
{
public int size() {
return stack.Count();
}
/* 判断栈是否为空 */
public bool isEmpty()
{
public bool isEmpty() {
return size() == 0;
}
/* 入栈 */
public void push(int num)
{
public void push(int num) {
stack.Add(num);
}
/* 出栈 */
public int pop()
{
public int pop() {
if (isEmpty())
throw new Exception();
var val = peek();
@ -47,25 +41,21 @@ class ArrayStack
}
/* 访问栈顶元素 */
public int peek()
{
public int peek() {
if (isEmpty())
throw new Exception();
return stack[size() - 1];
}
/* 将 List 转化为 Array 并返回 */
public int[] toArray()
{
public int[] toArray() {
return stack.ToArray();
}
}
public class array_stack
{
public class array_stack {
[Test]
public void Test()
{
public void Test() {
/* 初始化栈 */
ArrayStack stack = new ArrayStack();

6
codes/csharp/chapter_stack_and_queue/deque.cs
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@ -8,11 +8,9 @@ using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue;
public class deque
{
public class deque {
[Test]
public void Test()
{
public void Test() {
/* 初始化双向队列 */
// 在 C# 中，将链表 LinkedList 看作双向队列来使用
LinkedList<int> deque = new LinkedList<int>();

81
codes/csharp/chapter_stack_and_queue/linkedlist_deque.cs
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@ -6,17 +6,14 @@
using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue
{
namespace hello_algo.chapter_stack_and_queue {
/* 双向链表节点 */
public class ListNode
{
public class ListNode {
public int val; // 节点值
public ListNode? next; // 后继节点引用（指针）
public ListNode? prev; // 前驱节点引用（指针）
public ListNode(int val)
{
public ListNode(int val) {
this.val = val;
prev = null;
next = null;
@ -24,50 +21,42 @@ namespace hello_algo.chapter_stack_and_queue
}
/* 基于双向链表实现的双向队列 */
public class LinkedListDeque
{
public class LinkedListDeque {
private ListNode? front, rear; // 头节点 front, 尾节点 rear
private int queSize = 0; // 双向队列的长度
public LinkedListDeque()
{
public LinkedListDeque() {
front = null;
rear = null;
}
/* 获取双向队列的长度 */
public int size()
{
public int size() {
return queSize;
}
/* 判断双向队列是否为空 */
public bool isEmpty()
{
public bool isEmpty() {
return size() == 0;
}
/* 入队操作 */
private void push(int num, bool isFront)
{
private void push(int num, bool isFront) {
ListNode node = new ListNode(num);
// 若链表为空，则令 front, rear 都指向 node
if (isEmpty())
{
if (isEmpty()) {
front = node;
rear = node;
}
// 队首入队操作
else if (isFront)
{
else if (isFront) {
// 将 node 添加至链表头部
front.prev = node;
node.next = front;
front = node; // 更新头节点
}
// 队尾入队操作
else
{
else {
// 将 node 添加至链表尾部
rear.next = node;
node.prev = rear;
@ -78,35 +67,29 @@ namespace hello_algo.chapter_stack_and_queue
}
/* 队首入队 */
public void pushFirst(int num)
{
public void pushFirst(int num) {
push(num, true);
}
/* 队尾入队 */
public void pushLast(int num)
{
public void pushLast(int num) {
push(num, false);
}
/* 出队操作 */
private int? pop(bool isFront)
{
private int? pop(bool isFront) {
// 若队列为空，直接返回 null
if (isEmpty())
{
if (isEmpty()) {
return null;
}
int val;
// 队首出队操作
if (isFront)
{
if (isFront) {
val = front.val; // 暂存头节点值
// 删除头节点
ListNode fNext = front.next;
if (fNext != null)
{
if (fNext != null) {
fNext.prev = null;
front.next = null;
}
@ -114,13 +97,11 @@ namespace hello_algo.chapter_stack_and_queue
front = fNext; // 更新头节点
}
// 队尾出队操作
else
{
else {
val = rear.val; // 暂存尾节点值
// 删除尾节点
ListNode rPrev = rear.prev;
if (rPrev != null)
{
if (rPrev != null) {
rPrev.next = null;
rear.prev = null;
}
@ -133,36 +114,30 @@ namespace hello_algo.chapter_stack_and_queue
}
/* 队首出队 */
public int? popFirst()
{
public int? popFirst() {
return pop(true);
}
/* 队尾出队 */
public int? popLast()
{
public int? popLast() {
return pop(false);
}
/* 访问队首元素 */
public int? peekFirst()
{
public int? peekFirst() {
return isEmpty() ? null : front.val;
}
/* 访问队尾元素 */
public int? peekLast()
{
public int? peekLast() {
return isEmpty() ? null : rear.val;
}
/* 返回数组用于打印 */
public int[] toArray()
{
public int[] toArray() {
ListNode node = front;
int[] res = new int[size()];
for (int i = 0; i < res.Length; i++)
{
for (int i = 0; i < res.Length; i++) {
res[i] = node.val;
node = node.next;
}
@ -171,11 +146,9 @@ namespace hello_algo.chapter_stack_and_queue
}
}
public class linkedlist_deque
{
public class linkedlist_deque {
[Test]
public void Test()
{
public void Test() {
/* 初始化双向队列 */
LinkedListDeque deque = new LinkedListDeque();
deque.pushLast(3);

40
codes/csharp/chapter_stack_and_queue/linkedlist_queue.cs
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@ -10,43 +10,35 @@ using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue;
/* 基于链表实现的队列 */
class LinkedListQueue
{
class LinkedListQueue {
private ListNode? front, rear; // 头节点 front ，尾节点 rear
private int queSize = 0;
public LinkedListQueue()
{
public LinkedListQueue() {
front = null;
rear = null;
}
/* 获取队列的长度 */
public int size()
{
public int size() {
return queSize;
}
/* 判断队列是否为空 */
public bool isEmpty()
{
public bool isEmpty() {
return size() == 0;
}
/* 入队 */
public void push(int num)
{
public void push(int num) {
// 尾节点后添加 num
ListNode node = new ListNode(num);
// 如果队列为空，则令头、尾节点都指向该节点
if (front == null)
{
if (front == null) {
front = node;
rear = node;
// 如果队列不为空，则将该节点添加到尾节点后
}
else if (rear != null)
{
} else if (rear != null) {
rear.next = node;
rear = node;
}
@ -54,8 +46,7 @@ class LinkedListQueue
}
/* 出队 */
public int pop()
{
public int pop() {
int num = peek();
// 删除头节点
front = front?.next;
@ -64,23 +55,20 @@ class LinkedListQueue
}
/* 访问队首元素 */
public int peek()
{
public int peek() {
if (size() == 0 || front == null)
throw new Exception();
return front.val;
}
/* 将链表转化为 Array 并返回 */
public int[] toArray()
{
public int[] toArray() {
if (front == null)
return Array.Empty<int>();
ListNode node = front;
int[] res = new int[size()];
for (int i = 0; i < res.Length; i++)
{
for (int i = 0; i < res.Length; i++) {
res[i] = node.val;
node = node.next;
}
@ -88,11 +76,9 @@ class LinkedListQueue
}
}
public class linkedlist_queue
{
public class linkedlist_queue {
[Test]
public void Test()
{
public void Test() {
/* 初始化队列 */
LinkedListQueue queue = new LinkedListQueue();

33
codes/csharp/chapter_stack_and_queue/linkedlist_stack.cs
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@ -10,31 +10,26 @@ using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue;
/* 基于链表实现的栈 */
class LinkedListStack
{
class LinkedListStack {
private ListNode? stackPeek; // 将头节点作为栈顶
private int stkSize = 0; // 栈的长度
public LinkedListStack()
{
public LinkedListStack() {
stackPeek = null;
}
/* 获取栈的长度 */
public int size()
{
public int size() {
return stkSize;
}
/* 判断栈是否为空 */
public bool isEmpty()
{
public bool isEmpty() {
return size() == 0;
}
/* 入栈 */
public void push(int num)
{
public void push(int num) {
ListNode node = new ListNode(num);
node.next = stackPeek;
stackPeek = node;
@ -42,8 +37,7 @@ class LinkedListStack
}
/* 出栈 */
public int pop()
{
public int pop() {
if (stackPeek == null)
throw new Exception();
@ -54,23 +48,20 @@ class LinkedListStack
}
/* 访问栈顶元素 */
public int peek()
{
public int peek() {
if (size() == 0 || stackPeek == null)
throw new Exception();
return stackPeek.val;
}
/* 将 List 转化为 Array 并返回 */
public int[] toArray()
{
public int[] toArray() {
if (stackPeek == null)
return Array.Empty<int>();
ListNode node = stackPeek;
int[] res = new int[size()];
for (int i = res.Length - 1; i >= 0; i--)
{
for (int i = res.Length - 1; i >= 0; i--) {
res[i] = node.val;
node = node.next;
}
@ -78,11 +69,9 @@ class LinkedListStack
}
}
public class linkedlist_stack
{
public class linkedlist_stack {
[Test]
public void Test()
{
public void Test() {
/* 初始化栈 */
LinkedListStack stack = new LinkedListStack();

6
codes/csharp/chapter_stack_and_queue/queue.cs
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@ -8,11 +8,9 @@ using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue;
public class queue
{
public class queue {
[Test]
public void Test()
{
public void Test() {
/* 初始化队列 */
Queue<int> queue = new();

6
codes/csharp/chapter_stack_and_queue/stack.cs
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@ -8,11 +8,9 @@ using NUnit.Framework;
namespace hello_algo.chapter_stack_and_queue;
public class stack
{
public class stack {
[Test]
public void Test()
{
public void Test() {
/* 初始化栈 */
Stack<int> stack = new();

84
codes/csharp/chapter_tree/avl_tree.cs
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@ -10,27 +10,23 @@ using NUnit.Framework;
namespace hello_algo.chapter_tree;
/* AVL 树 */
class AVLTree
{
class AVLTree {
public TreeNode? root; // 根节点
/* 获取节点高度 */
public int height(TreeNode? node)
{
public int height(TreeNode? node) {
// 空节点高度为 -1 ，叶节点高度为 0
return node == null ? -1 : node.height;
}
/* 更新节点高度 */
private void updateHeight(TreeNode node)
{
private void updateHeight(TreeNode node) {
// 节点高度等于最高子树高度 + 1
node.height = Math.Max(height(node.left), height(node.right)) + 1;
}
/* 获取平衡因子 */
public int balanceFactor(TreeNode? node)
{
public int balanceFactor(TreeNode? node) {
// 空节点平衡因子为 0
if (node == null) return 0;
// 节点平衡因子 = 左子树高度 - 右子树高度
@ -38,8 +34,7 @@ class AVLTree
}
/* 右旋操作 */
TreeNode? rightRotate(TreeNode? node)
{
TreeNode? rightRotate(TreeNode? node) {
TreeNode? child = node.left;
TreeNode? grandChild = child?.right;
// 以 child 为原点，将 node 向右旋转
@ -53,8 +48,7 @@ class AVLTree
}
/* 左旋操作 */
TreeNode? leftRotate(TreeNode? node)
{
TreeNode? leftRotate(TreeNode? node) {
TreeNode? child = node.right;
TreeNode? grandChild = child?.left;
// 以 child 为原点，将 node 向左旋转
@ -68,35 +62,26 @@ class AVLTree
}
/* 执行旋转操作，使该子树重新恢复平衡 */
TreeNode? rotate(TreeNode? node)
{
TreeNode? rotate(TreeNode? node) {
// 获取节点 node 的平衡因子
int balanceFactorInt = balanceFactor(node);
// 左偏树
if (balanceFactorInt > 1)
{
if (balanceFactor(node.left) >= 0)
{
if (balanceFactorInt > 1) {
if (balanceFactor(node.left) >= 0) {
// 右旋
return rightRotate(node);
}
else
{
} else {
// 先左旋后右旋
node.left = leftRotate(node?.left);
return rightRotate(node);
}
}
// 右偏树
if (balanceFactorInt < -1)
{
if (balanceFactor(node.right) <= 0)
{
if (balanceFactorInt < -1) {
if (balanceFactor(node.right) <= 0) {
// 左旋
return leftRotate(node);
}
else
{
} else {
// 先右旋后左旋
node.right = rightRotate(node?.right);
return leftRotate(node);
@ -107,14 +92,12 @@ class AVLTree
}
/* 插入节点 */
public void insert(int val)
{
public void insert(int val) {
root = insertHelper(root, val);
}
/* 递归插入节点（辅助方法） */
private TreeNode? insertHelper(TreeNode? node, int val)
{
private TreeNode? insertHelper(TreeNode? node, int val) {
if (node == null) return new TreeNode(val);
/* 1. 查找插入位置，并插入节点 */
if (val < node.val)
@ -131,24 +114,20 @@ class AVLTree
}
/* 删除节点 */
public void remove(int val)
{
public void remove(int val) {
root = removeHelper(root, val);
}
/* 递归删除节点（辅助方法） */
private TreeNode? removeHelper(TreeNode? node, int val)
{
private TreeNode? removeHelper(TreeNode? node, int val) {
if (node == null) return null;
/* 1. 查找节点，并删除之 */
if (val < node.val)
node.left = removeHelper(node.left, val);
else if (val > node.val)
node.right = removeHelper(node.right, val);
else
{
if (node.left == null || node.right == null)
{
else {
if (node.left == null || node.right == null) {
TreeNode? child = node.left != null ? node.left : node.right;
// 子节点数量 = 0 ，直接删除 node 并返回
if (child == null)
@ -156,13 +135,10 @@ class AVLTree
// 子节点数量 = 1 ，直接删除 node
else
node = child;
}
else
{
} else {
// 子节点数量 = 2 ，则将中序遍历的下个节点删除，并用该节点替换当前节点
TreeNode? temp = node.right;
while (temp.left != null)
{
while (temp.left != null) {
temp = temp.left;
}
node.right = removeHelper(node.right, temp.val);
@ -177,12 +153,10 @@ class AVLTree
}
/* 查找节点 */
public TreeNode? search(int val)
{
public TreeNode? search(int val) {
TreeNode? cur = root;
// 循环查找，越过叶节点后跳出
while (cur != null)
{
while (cur != null) {
// 目标节点在 cur 的右子树中
if (cur.val < val)
cur = cur.right;
@ -198,25 +172,21 @@ class AVLTree
}
}
public class avl_tree
{
static void testInsert(AVLTree tree, int val)
{
public class avl_tree {
static void testInsert(AVLTree tree, int val) {
tree.insert(val);
Console.WriteLine("\n插入节点 " + val + " 后，AVL 树为");
PrintUtil.PrintTree(tree.root);
}
static void testRemove(AVLTree tree, int val)
{
static void testRemove(AVLTree tree, int val) {
tree.remove(val);
Console.WriteLine("\n删除节点 " + val + " 后，AVL 树为");
PrintUtil.PrintTree(tree.root);
}
[Test]
public void Test()
{
public void Test() {
/* 初始化空 AVL 树 */
AVLTree avlTree = new AVLTree();

55
codes/csharp/chapter_tree/binary_search_tree.cs
View File

@ -9,25 +9,21 @@ using NUnit.Framework;
namespace hello_algo.chapter_tree;
class BinarySearchTree
{
class BinarySearchTree {
TreeNode? root;
public BinarySearchTree(int[] nums)
{
public BinarySearchTree(int[] nums) {
Array.Sort(nums); // 排序数组
root = buildTree(nums, 0, nums.Length - 1); // 构建二叉搜索树
}
/* 获取二叉树根节点 */
public TreeNode? getRoot()
{
public TreeNode? getRoot() {
return root;
}
/* 构建二叉搜索树 */
public TreeNode? buildTree(int[] nums, int i, int j)
{
public TreeNode? buildTree(int[] nums, int i, int j) {
if (i > j) return null;
// 将数组中间节点作为根节点
int mid = (i + j) / 2;
@ -39,12 +35,10 @@ class BinarySearchTree
}
/* 查找节点 */
public TreeNode? search(int num)
{
public TreeNode? search(int num) {
TreeNode? cur = root;
// 循环查找，越过叶节点后跳出
while (cur != null)
{
while (cur != null) {
// 目标节点在 cur 的右子树中
if (cur.val < num) cur = cur.right;
// 目标节点在 cur 的左子树中
@ -57,14 +51,12 @@ class BinarySearchTree
}
/* 插入节点 */
public void insert(int num)
{
public void insert(int num) {
// 若树为空，直接提前返回
if (root == null) return;
TreeNode? cur = root, pre = null;
// 循环查找，越过叶节点后跳出
while (cur != null)
{
while (cur != null) {
// 找到重复节点，直接返回
if (cur.val == num) return;
pre = cur;
@ -76,8 +68,7 @@ class BinarySearchTree
// 插入节点 val
TreeNode node = new TreeNode(num);
if (pre != null)
{
if (pre != null) {
if (pre.val < num) pre.right = node;
else pre.left = node;
}
@ -85,14 +76,12 @@ class BinarySearchTree
/* 删除节点 */
public void remove(int num)
{
public void remove(int num) {
// 若树为空，直接提前返回
if (root == null) return;
TreeNode? cur = root, pre = null;
// 循环查找，越过叶节点后跳出
while (cur != null)
{
while (cur != null) {
// 找到待删除节点，跳出循环
if (cur.val == num) break;
pre = cur;
@ -104,27 +93,21 @@ class BinarySearchTree
// 若无待删除节点，则直接返回
if (cur == null || pre == null) return;
// 子节点数量 = 0 or 1
if (cur.left == null || cur.right == null)
{
if (cur.left == null || cur.right == null) {
// 当子节点数量 = 0 / 1 时， child = null / 该子节点
TreeNode? child = cur.left != null ? cur.left : cur.right;
// 删除节点 cur
if (pre.left == cur)
{
if (pre.left == cur) {
pre.left = child;
}
else
{
} else {
pre.right = child;
}
}
// 子节点数量 = 2
else
{
else {
// 获取中序遍历中 cur 的下一个节点
TreeNode? tmp = cur.right;
while (tmp.left != null)
{
while (tmp.left != null) {
tmp = tmp.left;
}
// 递归删除节点 tmp
@ -135,11 +118,9 @@ class BinarySearchTree
}
}
public class binary_search_tree
{
public class binary_search_tree {
[Test]
public void Test()
{
public void Test() {
/* 初始化二叉搜索树 */
int[] nums = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 };
BinarySearchTree bst = new BinarySearchTree(nums);

6
codes/csharp/chapter_tree/binary_tree.cs
View File

@ -9,11 +9,9 @@ using NUnit.Framework;
namespace hello_algo.chapter_tree;
public class binary_tree
{
public class binary_tree {
[Test]
public void Test()
{
public void Test() {
/* 初始化二叉树 */
// 初始化节点
TreeNode n1 = new TreeNode(1);

12
codes/csharp/chapter_tree/binary_tree_bfs.cs
View File

@ -9,19 +9,16 @@ using NUnit.Framework;
namespace hello_algo.chapter_tree;
public class binary_tree_bfs
{
public class binary_tree_bfs {
/* 层序遍历 */
public List<int> levelOrder(TreeNode root)
{
public List<int> levelOrder(TreeNode root) {
// 初始化队列，加入根节点
Queue<TreeNode> queue = new();
queue.Enqueue(root);
// 初始化一个列表，用于保存遍历序列
List<int> list = new();
while (queue.Count != 0)
{
while (queue.Count != 0) {
TreeNode node = queue.Dequeue(); // 队列出队
list.Add(node.val); // 保存节点值
if (node.left != null)
@ -33,8 +30,7 @@ public class binary_tree_bfs
}
[Test]
public void Test()
{
public void Test() {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
TreeNode? root = TreeNode.ListToTree(new List<int?> { 1, 2, 3, 4, 5, 6, 7 });

15
codes/csharp/chapter_tree/binary_tree_dfs.cs
View File

@ -9,13 +9,11 @@ using NUnit.Framework;
namespace hello_algo.chapter_tree;
public class binary_tree_dfs
{
public class binary_tree_dfs {
List<int> list = new();
/* 前序遍历 */
void preOrder(TreeNode? root)
{
void preOrder(TreeNode? root) {
if (root == null) return;
// 访问优先级：根节点 -> 左子树 -> 右子树
list.Add(root.val);
@ -24,8 +22,7 @@ public class binary_tree_dfs
}
/* 中序遍历 */
void inOrder(TreeNode? root)
{
void inOrder(TreeNode? root) {
if (root == null) return;
// 访问优先级：左子树 -> 根节点 -> 右子树
inOrder(root.left);
@ -34,8 +31,7 @@ public class binary_tree_dfs
}
/* 后序遍历 */
void postOrder(TreeNode? root)
{
void postOrder(TreeNode? root) {
if (root == null) return;
// 访问优先级：左子树 -> 右子树 -> 根节点
postOrder(root.left);
@ -44,8 +40,7 @@ public class binary_tree_dfs
}
[Test]
public void Test()
{
public void Test() {
/* 初始化二叉树 */
// 这里借助了一个从数组直接生成二叉树的函数
TreeNode? root = TreeNode.ListToTree(new List<int?> { 1, 2, 3, 4, 5, 6, 7 });

45
codes/csharp/include/ListNode.cs
View File

@ -4,61 +4,38 @@
namespace hello_algo.include;
/// <summary>
/// Definition for a singly-linked list node
/// </summary>
public class ListNode
{
/* Definition for a singly-linked list node */
public class ListNode {
public int val;
public ListNode? next;
/// <summary>
/// Generate a linked list with an array
/// </summary>
/// <param name="x"></param>
public ListNode(int x)
{
public ListNode(int x) {
val = x;
}
/// <summary>
/// Generate a linked list with an array
/// </summary>
/// <param name="arr"></param>
/// <returns></returns>
public static ListNode? ArrToLinkedList(int[] arr)
{
/* Generate a linked list with an array */
public static ListNode? ArrToLinkedList(int[] arr) {
ListNode dum = new ListNode(0);
ListNode head = dum;
foreach (int val in arr)
{
foreach (int val in arr) {
head.next = new ListNode(val);
head = head.next;
}
return dum.next;
}
/// <summary>
/// Get a list node with specific value from a linked list
/// </summary>
/// <param name="head"></param>
/// <param name="val"></param>
/// <returns></returns>
public static ListNode? GetListNode(ListNode? head, int val)
{
while (head != null && head.val != val)
{
/* Get a list node with specific value from a linked list */
public static ListNode? GetListNode(ListNode? head, int val) {
while (head != null && head.val != val) {
head = head.next;
}
return head;
}
public override string? ToString()
{
public override string? ToString() {
List<string> list = new();
var head = this;
while (head != null)
{
while (head != null) {
list.Add(head.val.ToString());
head = head.next;
}

106
codes/csharp/include/PrintUtil.cs
View File

@ -6,60 +6,44 @@
namespace hello_algo.include;
public class Trunk
{
public class Trunk {
public Trunk? prev;
public string str;
public Trunk(Trunk? prev, string str)
{
public Trunk(Trunk? prev, string str) {
this.prev = prev;
this.str = str;
}
};
public class PrintUtil
{
/**
* Print a list
* @param list
*/
public static void PrintList<T>(List<T> list)
{
public class PrintUtil {
/* Print a list */
public static void PrintList<T>(List<T> list) {
Console.WriteLine("[" + string.Join(", ", list) + "]");
}
/* Print a matrix (Array) */
public static void PrintMatrix<T>(T[][] matrix)
{
public static void PrintMatrix<T>(T[][] matrix) {
Console.WriteLine("[");
foreach (T[] row in matrix)
{
foreach (T[] row in matrix) {
Console.WriteLine(" " + string.Join(", ", row) + ",");
}
Console.WriteLine("]");
}
/* Print a matrix (List) */
public static void PrintMatrix<T>(List<List<T>> matrix)
{
public static void PrintMatrix<T>(List<List<T>> matrix) {
Console.WriteLine("[");
foreach (List<T> row in matrix)
{
foreach (List<T> row in matrix) {
Console.WriteLine(" " + string.Join(", ", row) + ",");
}
Console.WriteLine("]");
}
/**
* Print a linked list
* @param head
*/
public static void PrintLinkedList(ListNode head)
{
/* Print a linked list */
public static void PrintLinkedList(ListNode head) {
List<string> list = new();
while (head != null)
{
while (head != null) {
list.Add(head.val.ToString());
head = head.next;
}
@ -70,23 +54,14 @@ public class PrintUtil
* The interface of the tree printer
* This tree printer is borrowed from TECHIE DELIGHT
* https://www.techiedelight.com/c-program-print-binary-tree/
* @param root
*/
public static void PrintTree(TreeNode? root)
{
public static void PrintTree(TreeNode? root) {
PrintTree(root, null, false);
}
/**
* Print a binary tree
* @param root
* @param prev
* @param isLeft
*/
public static void PrintTree(TreeNode? root, Trunk? prev, bool isLeft)
{
if (root == null)
{
/* Print a binary tree */
public static void PrintTree(TreeNode? root, Trunk? prev, bool isLeft) {
if (root == null) {
return;
}
@ -95,17 +70,12 @@ public class PrintUtil
PrintTree(root.right, trunk, true);
if (prev == null)
{
if (prev == null) {
trunk.str = "———";
}
else if (isLeft)
{
} else if (isLeft) {
trunk.str = "/———";
prev_str = " |";
}
else
{
} else {
trunk.str = "\\———";
prev.str = prev_str;
}
@ -113,8 +83,7 @@ public class PrintUtil
ShowTrunks(trunk);
Console.WriteLine(" " + root.val);
if (prev != null)
{
if (prev != null) {
prev.str = prev_str;
}
trunk.str = " |";
@ -122,14 +91,9 @@ public class PrintUtil
PrintTree(root.left, trunk, false);
}
/**
* Helper function to print branches of the binary tree
* @param p
*/
public static void ShowTrunks(Trunk? p)
{
if (p == null)
{
/* Helper function to print branches of the binary tree */
public static void ShowTrunks(Trunk? p) {
if (p == null) {
return;
}
@ -137,22 +101,15 @@ public class PrintUtil
Console.Write(p.str);
}
/**
* Print a hash map
* @param <K>
* @param <V>
* @param map
*/
public static void PrintHashMap<K, V>(Dictionary<K, V> map) where K : notnull
{
foreach (var kv in map.Keys)
{
/* Print a hash map */
public static void PrintHashMap<K, V>(Dictionary<K, V> map) where K : notnull {
foreach (var kv in map.Keys) {
Console.WriteLine(kv.ToString() + " -> " + map[kv]?.ToString());
}
}
public static void PrintHeap(Queue<int> queue)
{
/* Print a heap */
public static void PrintHeap(Queue<int> queue) {
Console.Write("堆的数组表示：");
List<int> list = queue.ToList();
Console.WriteLine(string.Join(',', list));
@ -161,13 +118,12 @@ public class PrintUtil
PrintTree(tree);
}
public static void PrintHeap(PriorityQueue<int, int> queue)
{
/* Print a PriorityQueue */
public static void PrintHeap(PriorityQueue<int, int> queue) {
var newQueue = new PriorityQueue<int, int>(queue.UnorderedItems, queue.Comparer);
Console.Write("堆的数组表示：");
List<int> list = new List<int>();
while (newQueue.TryDequeue(out int element, out int priority))
{
while (newQueue.TryDequeue(out int element, out int priority)) {
list.Add(element);
}
Console.WriteLine("堆的树状表示：");

54
codes/csharp/include/TreeNode.cs
View File

@ -6,25 +6,19 @@
namespace hello_algo.include;
public class TreeNode
{
/* 二叉树节点类 */
public class TreeNode {
public int val; // 节点值
public int height; // 节点高度
public TreeNode? left; // 左子节点引用
public TreeNode? right; // 右子节点引用
public TreeNode(int x)
{
public TreeNode(int x) {
val = x;
}
/**
* Generate a binary tree given an array
* @param arr
* @return
*/
public static TreeNode? ListToTree(List<int?> arr)
{
/* Generate a binary tree given an array */
public static TreeNode? ListToTree(List<int?> arr) {
if (arr.Count == 0 || arr[0] == null)
return null;
@ -32,18 +26,15 @@ public class TreeNode
Queue<TreeNode> queue = new Queue<TreeNode>();
queue.Enqueue(root);
int i = 0;
while (queue.Count != 0)
{
while (queue.Count != 0) {
TreeNode node = queue.Dequeue();
if (++i >= arr.Count) break;
if (arr[i] != null)
{
if (arr[i] != null) {
node.left = new TreeNode((int)arr[i]);
queue.Enqueue(node.left);
}
if (++i >= arr.Count) break;
if (arr[i] != null)
{
if (arr[i] != null) {
node.right = new TreeNode((int)arr[i]);
queue.Enqueue(node.right);
}
@ -51,41 +42,26 @@ public class TreeNode
return root;
}
/**
* Serialize a binary tree to a list
* @param root
* @return
*/
public static List<int?> TreeToList(TreeNode root)
{
/* Serialize a binary tree to a list */
public static List<int?> TreeToList(TreeNode root) {
List<int?> list = new();
if (root == null) return list;
Queue<TreeNode?> queue = new();
while (queue.Count != 0)
{
while (queue.Count != 0) {
TreeNode? node = queue.Dequeue();
if (node != null)
{
if (node != null) {
list.Add(node.val);
queue.Enqueue(node.left);
queue.Enqueue(node.right);
}
else
{
} else {
list.Add(null);
}
}
return list;
}
/**
* Get a tree node with specific value in a binary tree
* @param root
* @param val
* @return
*/
public static TreeNode? GetTreeNode(TreeNode? root, int val)
{
/* Get a tree node with specific value in a binary tree */
public static TreeNode? GetTreeNode(TreeNode? root, int val) {
if (root == null)
return null;
if (root.val == val)

18
codes/csharp/include/Vertex.cs
View File

@ -7,31 +7,25 @@
namespace hello_algo.include;
/* 顶点类 */
public class Vertex
{
public class Vertex {
public int val;
public Vertex(int val)
{
public Vertex(int val) {
this.val = val;
}
/* 输入值列表 vals ，返回顶点列表 vets */
public static Vertex[] ValsToVets(int[] vals)
{
public static Vertex[] ValsToVets(int[] vals) {
Vertex[] vets = new Vertex[vals.Length];
for (int i = 0; i < vals.Length; i++)
{
for (int i = 0; i < vals.Length; i++) {
vets[i] = new Vertex(vals[i]);
}
return vets;
}
/* 输入顶点列表 vets ，返回值列表 vals */
public static List<int> VetsToVals(List<Vertex> vets)
{
public static List<int> VetsToVals(List<Vertex> vets) {
List<int> vals = new List<int>();
foreach (Vertex vet in vets)
{
foreach (Vertex vet in vets) {
vals.Add(vet.val);
}
return vals;