add zig codes for Section 'Hash Map', 'Linear Search' and 'Heap'

codes/zig/build.zig

@@ -174,6 +174,20 @@ pub fn build(b: *std.build.Builder) void {
         const run_step_hash_map= b.step("run_hash_map", "Run hash_map");
         run_step_hash_map.dependOn(&run_cmd_hash_map.step);
 
+    // Section: "Heap"
+        // Source File: "chapter_heap/heap.zig"
+        // Run Command: zig build run_heap
+        const exe_heap = b.addExecutable("heap", "chapter_heap/heap.zig");
+        exe_heap.addPackagePath("include", "include/include.zig");
+        exe_heap.setTarget(target);
+        exe_heap.setBuildMode(mode);
+        exe_heap.install();
+        const run_cmd_heap = exe_heap.run();
+        run_cmd_heap.step.dependOn(b.getInstallStep());
+        if (b.args) |args| run_cmd_heap.addArgs(args);
+        const run_step_heap = b.step("run_heap", "Run heap");
+        run_step_heap.dependOn(&run_cmd_heap.step);
+        
     // Section: "Linear Search"
         // Source File: "chapter_searching/linear_search.zig"
         // Run Command: zig build run_linear_search

codes/zig/chapter_heap/heap.zig

@@ -0,0 +1,85 @@
+// File: heap.zig
+// Created Time: 2023-01-14
+// Author: sjinzh (sjinzh@gmail.com)
+
+const std = @import("std");
+const inc = @import("include");
+
+fn lessThan(context: void, a: i32, b: i32) std.math.Order {
+    _ = context;
+    return std.math.order(a, b);
+}
+
+fn greaterThan(context: void, a: i32, b: i32) std.math.Order {
+    return lessThan(context, a, b).invert();
+}
+
+fn testPush(comptime T: type, mem_allocator: std.mem.Allocator, heap_push: anytype, val: T) !void {
+    var heap = heap_push;
+    try heap.add(val);  //元素入堆
+    std.debug.print("\n元素 {} 入堆后\n", .{val});
+    try inc.PrintUtil.printHeap(T, mem_allocator, heap);
+}
+
+fn testPop(comptime T: type, mem_allocator: std.mem.Allocator, heap_pop: anytype) !void {
+    var val = heap_pop.remove();    //堆顶元素出堆
+    std.debug.print("\n堆顶元素 {} 出堆后\n", .{val});
+    try inc.PrintUtil.printHeap(T, mem_allocator, heap_pop);
+}
+
+// Driver Code
+pub fn main() !void {
+    // 初始化内存分配器
+    var mem_arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    // 延迟释放内存
+    defer mem_arena.deinit();
+    const mem_allocator = mem_arena.allocator();
+
+    // 初始化堆
+    // 初始化小顶堆
+    const PQlt = std.PriorityQueue(i32, void, lessThan);
+    var minHeap = PQlt.init(std.heap.page_allocator, {});
+    defer minHeap.deinit();
+    // 初始化大顶堆
+    const PQgt = std.PriorityQueue(i32, void, greaterThan);
+    var maxHeap = PQgt.init(std.heap.page_allocator, {});
+    defer maxHeap.deinit();
+
+    std.debug.print("\n以下测试样例为大顶堆", .{});
+
+    // 元素入堆
+    try testPush(i32, mem_allocator, &maxHeap, 1);
+    try testPush(i32, mem_allocator, &maxHeap, 3);
+    try testPush(i32, mem_allocator, &maxHeap, 2);
+    try testPush(i32, mem_allocator, &maxHeap, 5);
+    try testPush(i32, mem_allocator, &maxHeap, 4);
+
+    // 获取堆顶元素
+    var peek = maxHeap.peek().?;
+    std.debug.print("\n堆顶元素为 {}\n", .{peek});
+
+    // 堆顶元素出堆
+    try testPop(i32, mem_allocator, &maxHeap);
+    try testPop(i32, mem_allocator, &maxHeap);
+    try testPop(i32, mem_allocator, &maxHeap);
+    try testPop(i32, mem_allocator, &maxHeap);
+    try testPop(i32, mem_allocator, &maxHeap);
+
+    // 获取堆的大小
+    var size = maxHeap.len;
+    std.debug.print("\n堆元素数量为 {}", .{size});
+
+    // 判断堆是否为空
+    var isEmpty = if (maxHeap.len == 0) true else false;
+    std.debug.print("\n堆是否为空 {}\n", .{isEmpty});
+
+    // 输入列表并建堆
+    // 时间复杂度为 O(n) ，而非 O(nlogn)
+    try minHeap.addSlice(&[_]i32{ 1, 3, 2, 5, 4 });
+    std.debug.print("\n输入列表并建立小顶堆后\n", .{});
+    try inc.PrintUtil.printHeap(i32, mem_allocator, minHeap);
+
+    const getchar = try std.io.getStdIn().reader().readByte();
+    _ = getchar;
+}
+

codes/zig/include/PrintUtil.zig

@@ -3,8 +3,10 @@
 // Author: sjinzh (sjinzh@gmail.com)
 
 const std = @import("std");
-const ListNode = @import("ListNode.zig").ListNode;
+pub const ListUtil = @import("ListNode.zig");
-const TreeNode = @import("TreeNode.zig").TreeNode;
+pub const ListNode = ListUtil.ListNode;
+pub const TreeUtil = @import("TreeNode.zig");
+pub const TreeNode = TreeUtil.TreeNode;
 
 // Print an array
 pub fn printArray(comptime T: type, nums: []T) void {
@@ -56,6 +58,17 @@ pub fn printHashMap(comptime TKey: type, comptime TValue: type, map: std.AutoHas
     }
 }
 
+// print a heap (PriorityQueue)
+pub fn printHeap(comptime T: type, mem_allocator: std.mem.Allocator, queue: anytype) !void {
+    var arr = queue.items;
+    var len = queue.len;
+    std.debug.print("堆的数组表示：", .{});
+    printArray(T, arr[0..len]);
+    std.debug.print("\n堆的树状表示：\n", .{});
+    var root = try TreeUtil.arrToTree(T, mem_allocator, arr[0..len]);
+    try printTree(root, null, false);
+}
+
 // This tree printer is borrowed from TECHIE DELIGHT
 // https://www.techiedelight.com/c-program-print-binary-tree/
 const Trunk = struct {

codes/zig/include/TreeNode.zig

@@ -21,4 +21,40 @@ pub fn TreeNode(comptime T: type) type {
             self.right = null;
         }
     };   
+}
+
+// Generate a binary tree with an array
+pub fn arrToTree(comptime T: type, mem_allocator: std.mem.Allocator, list: []T) !?*TreeNode(T) {
+    if (list.len == 0) return null;
+    var root = try mem_allocator.create(TreeNode(T));
+    root.init(list[0]);
+
+    const TailQueue = std.TailQueue(?*TreeNode(T));
+    const TailQueueNode = std.TailQueue(?*TreeNode(T)).Node;
+    var que = TailQueue{};
+    var node_root = TailQueueNode{ .data = root };
+    que.append(&node_root); 
+    var index: usize = 0;
+    while (que.len > 0) {
+        var node = que.popFirst();
+        index += 1;
+        if (index >= list.len) break;
+        if (index < list.len) {
+            var tmp = try mem_allocator.create(TreeNode(T));
+            tmp.init(list[index]);
+            node.?.data.?.left = tmp;
+            var a = TailQueueNode{ .data = node.?.data.?.left };
+            que.append(&a);
+        }
+        index += 1;
+        if (index >= list.len) break;
+        if (index < list.len) {
+            var tmp = try mem_allocator.create(TreeNode(T));
+            tmp.init(list[index]);
+            node.?.data.?.right = tmp;
+            var a = TailQueueNode{ .data = node.?.data.?.right };
+            que.append(&a);
+        }
+    }
+    return root;
 }