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feat: add Swift codes for chapter_sorting articles (#313)

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* feat: add Swift codes for bubble_sort article

* feat: add Swift codes for insertion_sort article

* feat: add Swift codes for quick_sort article

* feat: add Swift codes for merge_sort article

* feat: add Swift codes for radix_sort

* refactor: remove ^ operator
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nuomi1 2023-01-31 00:18:40 +08:00 committed by GitHub
parent 7f3752d306
commit f43f7a64b6
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10 changed files with 525 additions and 5 deletions
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10
codes/swift/Package.swift
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@ -31,6 +31,11 @@ let package = Package(
.executable(name: "linear_search", targets: ["linear_search"]),
.executable(name: "binary_search", targets: ["binary_search"]),
.executable(name: "hashing_search", targets: ["hashing_search"]),
.executable(name: "bubble_sort", targets: ["bubble_sort"]),
.executable(name: "insertion_sort", targets: ["insertion_sort"]),
.executable(name: "quick_sort", targets: ["quick_sort"]),
.executable(name: "merge_sort", targets: ["merge_sort"]),
.executable(name: "radix_sort", targets: ["radix_sort"]),
],
targets: [
.target(name: "utils", path: "utils"),
@ -60,5 +65,10 @@ let package = Package(
.executableTarget(name: "linear_search", dependencies: ["utils"], path: "chapter_searching", sources: ["linear_search.swift"]),
.executableTarget(name: "binary_search", path: "chapter_searching", sources: ["binary_search.swift"]),
.executableTarget(name: "hashing_search", dependencies: ["utils"], path: "chapter_searching", sources: ["hashing_search.swift"]),
.executableTarget(name: "bubble_sort", path: "chapter_sorting", sources: ["bubble_sort.swift"]),
.executableTarget(name: "insertion_sort", path: "chapter_sorting", sources: ["insertion_sort.swift"]),
.executableTarget(name: "quick_sort", path: "chapter_sorting", sources: ["quick_sort.swift"]),
.executableTarget(name: "merge_sort", path: "chapter_sorting", sources: ["merge_sort.swift"]),
.executableTarget(name: "radix_sort", path: "chapter_sorting", sources: ["radix_sort.swift"]),
]
)

55
codes/swift/chapter_sorting/bubble_sort.swift Normal file
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@ -0,0 +1,55 @@
/**
* File: bubble_sort.swift
* Created Time: 2023-01-29
* Author: nuomi1 (nuomi1@qq.com)
*/
/* 冒泡排序 */
func bubbleSort(nums: inout [Int]) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for i in stride(from: nums.count - 1, to: 0, by: -1) {
// 内循环：冒泡操作
for j in stride(from: 0, to: i, by: 1) {
if nums[j] > nums[j + 1] {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j]
nums[j] = nums[j + 1]
nums[j + 1] = tmp
}
}
}
}
/* 冒泡排序（标志优化）*/
func bubbleSortWithFlag(nums: inout [Int]) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for i in stride(from: nums.count - 1, to: 0, by: -1) {
var flag = false // 初始化标志位
for j in stride(from: 0, to: i, by: 1) {
if nums[j] > nums[j + 1] {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j]
nums[j] = nums[j + 1]
nums[j + 1] = tmp
flag = true // 记录交换元素
}
}
if !flag { // 此轮冒泡未交换任何元素，直接跳出
break
}
}
}
@main
enum BubbleSort {
/* Driver Code */
static func main() {
var nums = [4, 1, 3, 1, 5, 2]
bubbleSort(nums: &nums)
print("冒泡排序完成后 nums = \(nums)")
var nums1 = [4, 1, 3, 1, 5, 2]
bubbleSortWithFlag(nums: &nums1)
print("冒泡排序完成后 nums1 = \(nums1)")
}
}

30
codes/swift/chapter_sorting/insertion_sort.swift Normal file
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@ -0,0 +1,30 @@
/**
* File: insertion_sort.swift
* Created Time: 2023-01-29
* Author: nuomi1 (nuomi1@qq.com)
*/
/* 插入排序 */
func insertionSort(nums: inout [Int]) {
// 外循环：base = nums[1], nums[2], ..., nums[n-1]
for i in stride(from: 1, to: nums.count, by: 1) {
let base = nums[i]
var j = i - 1
// 内循环：将 base 插入到左边的正确位置
while j >= 0, nums[j] > base {
nums[j + 1] = nums[j] // 1. 将 nums[j] 向右移动一位
j -= 1
}
nums[j + 1] = base // 2. 将 base 赋值到正确位置
}
}
@main
enum InsertionSort {
/* Driver Code */
static func main() {
var nums = [4, 1, 3, 1, 5, 2]
insertionSort(nums: &nums)
print("插入排序完成后 nums = \(nums)")
}
}

67
codes/swift/chapter_sorting/merge_sort.swift Normal file
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@ -0,0 +1,67 @@
/**
* File: merge_sort.swift
* Created Time: 2023-01-29
* Author: nuomi1 (nuomi1@qq.com)
*/
/**
* 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]
*/
func merge(nums: inout [Int], left: Int, mid: Int, right: Int) {
// 初始化辅助数组
let tmp = Array(nums[left ..< (right + 1)])
// 左子数组的起始索引和结束索引
let leftStart = left - left
let leftEnd = mid - left
// 右子数组的起始索引和结束索引
let rightStart = mid + 1 - left
let rightEnd = right - left
// i, j 分别指向左子数组、右子数组的首元素
var i = leftStart
var j = rightStart
// 通过覆盖原数组 nums 来合并左子数组和右子数组
for k in left ... right {
// 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]
j += 1
}
// 否则，若“右子数组已全部合并完”或“左子数组元素 <= 右子数组元素”，则选取左子数组元素，并且 i++
else if j > rightEnd || tmp[i] <= tmp[j] {
nums[k] = tmp[i]
i += 1
}
// 否则，若“左右子数组都未全部合并完”且“左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
else {
nums[k] = tmp[j]
j += 1
}
}
}
/* 归并排序 */
func mergeSort(nums: inout [Int], left: Int, right: Int) {
// 终止条件
if left >= right { // 当子数组长度为 1 时终止递归
return
}
// 划分阶段
let mid = (left + right) / 2 // 计算中点
mergeSort(nums: &nums, left: left, right: mid) // 递归左子数组
mergeSort(nums: &nums, left: mid + 1, right: right) // 递归右子数组
// 合并阶段
merge(nums: &nums, left: left, mid: mid, right: right)
}
@main
enum MergeSort {
/* Driver Code */
static func main() {
/* 归并排序 */
var nums = [7, 3, 2, 6, 0, 1, 5, 4]
mergeSort(nums: &nums, left: 0, right: nums.count - 1)
print("归并排序完成后 nums = \(nums)")
}
}

124
codes/swift/chapter_sorting/quick_sort.swift Normal file
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@ -0,0 +1,124 @@
/**
* File: quick_sort.swift
* Created Time: 2023-01-29
* Author: nuomi1 (nuomi1@qq.com)
*/
/* 元素交换 */
func swap(nums: inout [Int], i: Int, j: Int) {
let tmp = nums[i]
nums[i] = nums[j]
nums[j] = tmp
}
/* 快速排序类 */
// 快速排序类-哨兵划分
func quickSortPartition(nums: inout [Int], left: Int, right: Int) -> Int {
// 以 nums[left] 作为基准数
var i = left
var j = right
while i < j {
while i < j, nums[j] >= nums[left] {
j -= 1 // 从右向左找首个小于基准数的元素
}
while i < j, nums[i] <= nums[left] {
i += 1 // 从左向右找首个大于基准数的元素
}
swap(nums: &nums, i: i, j: j) // 交换这两个元素
}
swap(nums: &nums, i: i, j: left) // 将基准数交换至两子数组的分界线
return i // 返回基准数的索引
}
// 快速排序类-快速排序
func quickSort(nums: inout [Int], left: Int, right: Int) {
// 子数组长度为 1 时终止递归
if left >= right {
return
}
// 哨兵划分
let pivot = quickSortPartition(nums: &nums, left: left, right: right)
// 递归左子数组、右子数组
quickSort(nums: &nums, left: left, right: pivot - 1)
quickSort(nums: &nums, left: pivot + 1, right: right)
}
/* 快速排序类（中位基准数优化） */
// 快速排序类（中位基准数优化）-选取三个元素的中位数
func quickSortMedianThree(nums: [Int], left: Int, mid: Int, right: Int) -> Int {
if (nums[left] < nums[mid]) != (nums[left] < nums[right]) {
return left
} else if (nums[mid] < nums[left]) != (nums[mid] < nums[right]) {
return mid
} else {
return right
}
}
// 快速排序类（中位基准数优化）-哨兵划分（三数取中值）
func quickSortMedianPartition(nums: inout [Int], left: Int, right: Int) -> Int {
// 选取三个候选元素的中位数
let med = quickSortMedianThree(nums: nums, left: left, mid: (left + right) / 2, right: right)
// 将中位数交换至数组最左端
swap(nums: &nums, i: left, j: med)
return quickSortPartition(nums: &nums, left: left, right: right)
}
// 快速排序类（中位基准数优化）-快速排序
func quickSortMedian(nums: inout [Int], left: Int, right: Int) {
// 子数组长度为 1 时终止递归
if left >= right {
return
}
// 哨兵划分
let pivot = quickSortMedianPartition(nums: &nums, left: left, right: right)
// 递归左子数组、右子数组
quickSortMedian(nums: &nums, left: left, right: pivot - 1)
quickSortMedian(nums: &nums, left: pivot + 1, right: right)
}
/* 快速排序类（尾递归优化） */
// 快速排序类（尾递归优化）-哨兵划分
func quickSortTailCallPartition(nums: inout [Int], left: Int, right: Int) -> Int {
quickSortPartition(nums: &nums, left: left, right: right)
}
// 快速排序类（尾递归优化）-快速排序（尾递归优化）
func quickSortTailCall(nums: inout [Int], left: Int, right: Int) {
var left = left
var right = right
// 子数组长度为 1 时终止
while left < right {
// 哨兵划分操作
let pivot = quickSortTailCallPartition(nums: &nums, left: left, right: right)
// 对两个子数组中较短的那个执行快排
if (pivot - left) < (right - pivot) {
quickSortTailCall(nums: &nums, left: left, right: 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 {
quickSortTailCall(nums: &nums, left: pivot + 1, right: right) // 递归排序右子数组
right = pivot - 1 // 剩余待排序区间为 [left, pivot - 1]
}
}
}
@main
enum QuickSort {
/* Driver Code */
static func main() {
/* 快速排序 */
var nums = [2, 4, 1, 0, 3, 5]
quickSort(nums: &nums, left: 0, right: nums.count - 1)
print("快速排序完成后 nums = \(nums)")
/* 快速排序（中位基准数优化） */
var nums1 = [2, 4, 1, 0, 3, 5]
quickSortMedian(nums: &nums1, left: 0, right: nums1.count - 1)
print("快速排序（中位基准数优化）完成后 nums1 = \(nums1)")
/* 快速排序（尾递归优化） */
var nums2 = [2, 4, 1, 0, 3, 5]
quickSortTailCall(nums: &nums2, left: 0, right: nums2.count - 1)
print("快速排序（尾递归优化）完成后 nums2 = \(nums2)")
}
}

70
codes/swift/chapter_sorting/radix_sort.swift Normal file
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@ -0,0 +1,70 @@
/**
* File: radix_sort.swift
* Created Time: 2023-01-29
* Author: nuomi1 (nuomi1@qq.com)
*/
/* 获取元素 num 的第 k 位，其中 exp = 10^(k-1) */
func digit(num: Int, exp: Int) -> Int {
// 传入 exp 而非 k 可以避免在此重复执行昂贵的次方计算
(num / exp) % 10
}
/* 计数排序（根据 nums 第 k 位排序） */
func countSort(nums: inout [Int], exp: Int) {
// 十进制的各位数字范围为 0~9 ，因此需要长度为 10 的桶
var bucket = Array(repeating: 0, count: 10)
let n = nums.count
// 借助桶来统计 0~9 各数字的出现次数
for i in nums.indices {
let d = digit(num: nums[i], exp: exp) // 获取 nums[i] 第 k 位，记为 d
bucket[d] += 1 // 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 i in 1 ..< 10 {
bucket[i] += bucket[i - 1]
}
// 倒序遍历，根据桶内统计结果，将各元素填入暂存数组 tmp
var tmp = Array(repeating: 0, count: n)
for i in stride(from: n - 1, through: 0, by: -1) {
let d = digit(num: nums[i], exp: exp)
let j = bucket[d] - 1 // 获取 d 在数组中的索引 j
tmp[j] = nums[i] // 将当前元素填入索引 j
bucket[d] -= 1 // 将 d 的数量减 1
}
// 将 tmp 复制到 nums
for i in nums.indices {
nums[i] = tmp[i]
}
}
/* 基数排序 */
func radixSort(nums: inout [Int]) {
// 获取数组的最大元素，用于判断最大位数
var ma = Int.min
for num in nums {
if num > ma {
ma = num
}
}
// 按照从低位到高位的顺序遍历
for exp in sequence(first: 1, next: { ma >= ($0 * 10) ? $0 * 10 : nil }) {
// 对数组元素的第 k 位执行「计数排序」
// k = 1 -> exp = 1
// k = 2 -> exp = 10
// k = 3 -> exp = 100
// 即 exp = 10^(k-1)
countSort(nums: &nums, exp: exp)
}
}
@main
enum RadixSort {
/* Driver Code */
static func main() {
/* 基数排序 */
var nums = [23, 12, 3, 4, 788, 192]
radixSort(nums: &nums)
print("基数排序完成后 nums = \(nums)")
}
}

36
docs/chapter_sorting/bubble_sort.md
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@ -215,7 +215,21 @@ comments: true
=== "Swift"
```swift title="bubble_sort.swift"
/* 冒泡排序 */
func bubbleSort(nums: inout [Int]) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for i in stride(from: nums.count - 1, to: 0, by: -1) {
// 内循环：冒泡操作
for j in stride(from: 0, to: i, by: 1) {
if nums[j] > nums[j + 1] {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j]
nums[j] = nums[j + 1]
nums[j + 1] = tmp
}
}
}
}
```
## 算法特性
@ -424,5 +438,23 @@ comments: true
=== "Swift"
```swift title="bubble_sort.swift"
/* 冒泡排序（标志优化）*/
func bubbleSortWithFlag(nums: inout [Int]) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for i in stride(from: nums.count - 1, to: 0, by: -1) {
var flag = false // 初始化标志位
for j in stride(from: 0, to: i, by: 1) {
if nums[j] > nums[j + 1] {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j]
nums[j] = nums[j + 1]
nums[j + 1] = tmp
flag = true // 记录交换元素
}
}
if !flag { // 此轮冒泡未交换任何元素，直接跳出
break
}
}
}
```

15
docs/chapter_sorting/insertion_sort.md
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@ -178,7 +178,20 @@ comments: true
=== "Swift"
```swift title="insertion_sort.swift"
/* 插入排序 */
func insertionSort(nums: inout [Int]) {
// 外循环：base = nums[1], nums[2], ..., nums[n-1]
for i in stride(from: 1, to: nums.count, by: 1) {
let base = nums[i]
var j = i - 1
// 内循环：将 base 插入到左边的正确位置
while j >= 0, nums[j] > base {
nums[j + 1] = nums[j] // 1. 将 nums[j] 向右移动一位
j -= 1
}
nums[j + 1] = base // 2. 将 base 赋值到正确位置
}
}
```
## 算法特性

49
docs/chapter_sorting/merge_sort.md
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@ -390,7 +390,56 @@ comments: true
=== "Swift"
```swift title="merge_sort.swift"
/**
* 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]
*/
func merge(nums: inout [Int], left: Int, mid: Int, right: Int) {
// 初始化辅助数组
let tmp = Array(nums[left ..< (right + 1)])
// 左子数组的起始索引和结束索引
let leftStart = left - left
let leftEnd = mid - left
// 右子数组的起始索引和结束索引
let rightStart = mid + 1 - left
let rightEnd = right - left
// i, j 分别指向左子数组、右子数组的首元素
var i = leftStart
var j = rightStart
// 通过覆盖原数组 nums 来合并左子数组和右子数组
for k in left ... right {
// 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]
j += 1
}
// 否则，若“右子数组已全部合并完”或“左子数组元素 <= 右子数组元素”，则选取左子数组元素，并且 i++
else if j > rightEnd || tmp[i] <= tmp[j] {
nums[k] = tmp[i]
i += 1
}
// 否则，若“左右子数组都未全部合并完”且“左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
else {
nums[k] = tmp[j]
j += 1
}
}
}
/* 归并排序 */
func mergeSort(nums: inout [Int], left: Int, right: Int) {
// 终止条件
if left >= right { // 当子数组长度为 1 时终止递归
return
}
// 划分阶段
let mid = (left + right) / 2 // 计算中点
mergeSort(nums: &nums, left: left, right: mid) // 递归左子数组
mergeSort(nums: &nums, left: mid + 1, right: right) // 递归右子数组
// 合并阶段
merge(nums: &nums, left: left, mid: mid, right: right)
}
```
下面重点解释一下合并方法 `merge()` 的流程：

74
docs/chapter_sorting/quick_sort.md
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@ -233,7 +233,30 @@ comments: true
=== "Swift"
```swift title="quick_sort.swift"
/* 元素交换 */
func swap(nums: inout [Int], i: Int, j: Int) {
let tmp = nums[i]
nums[i] = nums[j]
nums[j] = tmp
}
/* 哨兵划分 */
func partition(nums: inout [Int], left: Int, right: Int) -> Int {
// 以 nums[left] 作为基准数
var i = left
var j = right
while i < j {
while i < j, nums[j] >= nums[left] {
j -= 1 // 从右向左找首个小于基准数的元素
}
while i < j, nums[i] <= nums[left] {
i += 1 // 从左向右找首个大于基准数的元素
}
swap(nums: &nums, i: i, j: j) // 交换这两个元素
}
swap(nums: &nums, i: i, j: left) // 将基准数交换至两子数组的分界线
return i // 返回基准数的索引
}
```
!!! note "快速排序的分治思想"
@ -375,7 +398,18 @@ comments: true
=== "Swift"
```swift title="quick_sort.swift"
/* 快速排序 */
func quickSort(nums: inout [Int], left: Int, right: Int) {
// 子数组长度为 1 时终止递归
if left >= right {
return
}
// 哨兵划分
let pivot = partition(nums: &nums, left: left, right: right)
// 递归左子数组、右子数组
quickSort(nums: &nums, left: left, right: pivot - 1)
quickSort(nums: &nums, left: pivot + 1, right: right)
}
```
## 算法特性
@ -596,7 +630,26 @@ comments: true
=== "Swift"
```swift title="quick_sort.swift"
/* 选取三个元素的中位数 */
func medianThree(nums: [Int], left: Int, mid: Int, right: Int) -> Int {
if (nums[left] < nums[mid]) != (nums[left] < nums[right]) {
return left
} else if (nums[mid] < nums[left]) != (nums[mid] < nums[right]) {
return mid
} else {
return right
}
}
/* 哨兵划分（三数取中值） */
func partition(nums: inout [Int], left: Int, right: Int) -> Int {
// 选取三个候选元素的中位数
let med = medianThree(nums: nums, left: left, mid: (left + right) / 2, right: right)
// 将中位数交换至数组最左端
swap(nums: &nums, i: left, j: med)
// 以 nums[left] 作为基准数
// 下同省略...
}
```
## 尾递归优化
@ -763,5 +816,22 @@ comments: true
=== "Swift"
```swift title="quick_sort.swift"
/* 快速排序（尾递归优化） */
func quickSort(nums: inout [Int], left: Int, right: Int) {
var left = left
var right = right
// 子数组长度为 1 时终止
while left < right {
// 哨兵划分操作
let pivot = partition(nums: &nums, left: left, right: right)
// 对两个子数组中较短的那个执行快排
if (pivot - left) < (right - pivot) {
quickSort(nums: &nums, left: left, right: 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 {
quickSort(nums: &nums, left: pivot + 1, right: right) // 递归排序右子数组
right = pivot - 1 // 剩余待排序区间为 [left, pivot - 1]
}
}
}
```