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Merge remote-tracking branch 'origin/master'
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44df72e598
@ -24,7 +24,7 @@ func newHeap() *maxHeap {
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/* 构造函数,根据切片建堆 */
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func newMaxHeap(nums []any) *maxHeap {
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// 所有元素入堆
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// 将列表元素原封不动添加进堆
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h := &maxHeap{data: nums}
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for i := len(h.data) - 1; i >= 0; i-- {
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// 堆化除叶结点以外的其他所有结点
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@ -20,7 +20,7 @@ class MaxHeap {
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/* 构造函数,根据输入列表建堆 */
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public MaxHeap(List<Integer> nums) {
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// 所有元素入堆
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// 将列表元素原封不动添加进堆
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maxHeap = new ArrayList<>(nums);
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// 堆化除叶结点以外的其他所有结点
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for (int i = parent(size() - 1); i >= 0; i--) {
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@ -201,7 +201,20 @@ pub fn build(b: *std.build.Builder) void {
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if (b.args) |args| run_cmd_heap.addArgs(args);
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const run_step_heap = b.step("run_heap", "Run heap");
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run_step_heap.dependOn(&run_cmd_heap.step);
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// Source File: "chapter_heap/my_heap.zig"
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// Run Command: zig build run_my_heap
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const exe_my_heap = b.addExecutable("my_heap", "chapter_heap/my_heap.zig");
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exe_my_heap.addPackagePath("include", "include/include.zig");
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exe_my_heap.setTarget(target);
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exe_my_heap.setBuildMode(mode);
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exe_my_heap.install();
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const run_cmd_my_heap = exe_my_heap.run();
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run_cmd_my_heap.step.dependOn(b.getInstallStep());
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if (b.args) |args| run_cmd_my_heap.addArgs(args);
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const run_step_my_heap = b.step("run_my_heap", "Run my_heap");
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run_step_my_heap.dependOn(&run_cmd_my_heap.step);
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// Section: "Linear Search"
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// Source File: "chapter_searching/linear_search.zig"
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// Run Command: zig build run_linear_search
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190
codes/zig/chapter_heap/my_heap.zig
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190
codes/zig/chapter_heap/my_heap.zig
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@ -0,0 +1,190 @@
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// File: my_heap.zig
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// Created Time: 2023-01-14
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// Author: sjinzh (sjinzh@gmail.com)
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const std = @import("std");
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const inc = @import("include");
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// 堆类简易实现
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// 编译期泛型
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pub fn MaxHeap(comptime T: type) type {
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return struct {
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const Self = @This();
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maxHeap: ?std.ArrayList(T) = null, // 使用列表而非数组,这样无需考虑扩容问题
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// 构造函数,根据输入列表建堆
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pub fn init(self: *Self, allocator: std.mem.Allocator, nums: []const T) !void {
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if (self.maxHeap != null) return;
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self.maxHeap = std.ArrayList(T).init(allocator);
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// 将列表元素原封不动添加进堆
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try self.maxHeap.?.appendSlice(nums);
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// 堆化除叶结点以外的其他所有结点
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var i: usize = parent(self.size() - 1) + 1;
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while (i > 0) : (i -= 1) {
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try self.siftDown(i - 1);
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}
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}
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// 析构函数,释放内存
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pub fn deinit(self: *Self) void {
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if (self.maxHeap != null) self.maxHeap.?.deinit();
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}
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// 获取左子结点索引
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fn left(i: usize) usize {
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return 2 * i + 1;
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}
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// 获取右子结点索引
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fn right(i: usize) usize {
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return 2 * i + 2;
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}
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// 获取父结点索引
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fn parent(i: usize) usize {
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// return (i - 1) / 2; // 向下整除
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return @divFloor(i - 1, 2);
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}
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// 交换元素
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fn swap(self: *Self, i: usize, j: usize) !void {
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var a = self.maxHeap.?.items[i];
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var b = self.maxHeap.?.items[j];
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var tmp = a;
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try self.maxHeap.?.replaceRange(i, 1, &[_]T{b});
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try self.maxHeap.?.replaceRange(j, 1, &[_]T{tmp});
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}
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// 获取堆大小
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pub fn size(self: *Self) usize {
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return self.maxHeap.?.items.len;
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}
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// 判断堆是否为空
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pub fn isEmpty(self: *Self) bool {
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return self.size() == 0;
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}
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// 访问堆顶元素
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pub fn peek(self: *Self) T {
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return self.maxHeap.?.items[0];
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}
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// 元素入堆
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pub fn push(self: *Self, val: T) !void {
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// 添加结点
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try self.maxHeap.?.append(val);
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// 从底至顶堆化
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try self.siftUp(self.size() - 1);
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}
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// 从结点 i 开始,从底至顶堆化
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fn siftUp(self: *Self, i_: usize) !void {
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var i = i_;
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while (true) {
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// 获取结点 i 的父结点
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var p = parent(i);
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// 当“越过根结点”或“结点无需修复”时,结束堆化
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if (p < 0 or self.maxHeap.?.items[i] <= self.maxHeap.?.items[p]) break;
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// 交换两结点
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try self.swap(i, p);
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// 循环向上堆化
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i = p;
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}
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}
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// 元素出堆
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pub fn poll(self: *Self) !T {
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// 判断处理
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if (self.isEmpty()) unreachable;
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// 交换根结点与最右叶结点(即交换首元素与尾元素)
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try self.swap(0, self.size() - 1);
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// 删除结点
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var val = self.maxHeap.?.pop();
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// 从顶至底堆化
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try self.siftDown(0);
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// 返回堆顶元素
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return val;
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}
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// 从结点 i 开始,从顶至底堆化
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fn siftDown(self: *Self, i_: usize) !void {
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var i = i_;
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while (true) {
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// 判断结点 i, l, r 中值最大的结点,记为 ma
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var l = left(i);
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var r = right(i);
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var ma = i;
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if (l < self.size() and self.maxHeap.?.items[l] > self.maxHeap.?.items[ma]) ma = l;
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if (r < self.size() and self.maxHeap.?.items[r] > self.maxHeap.?.items[ma]) ma = r;
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// 若结点 i 最大或索引 l, r 越界,则无需继续堆化,跳出
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if (ma == i) break;
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// 交换两结点
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try self.swap(i, ma);
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// 循环向下堆化
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i = ma;
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}
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}
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fn lessThan(context: void, a: T, b: T) std.math.Order {
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_ = context;
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return std.math.order(a, b);
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}
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fn greaterThan(context: void, a: T, b: T) std.math.Order {
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return lessThan(context, a, b).invert();
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}
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// 打印堆(二叉树)
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pub fn print(self: *Self, mem_allocator: std.mem.Allocator) !void {
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const PQgt = std.PriorityQueue(T, void, greaterThan);
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var queue = PQgt.init(std.heap.page_allocator, {});
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defer queue.deinit();
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try queue.addSlice(self.maxHeap.?.items);
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try inc.PrintUtil.printHeap(T, mem_allocator, queue);
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}
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};
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}
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// Driver Code
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pub fn main() !void {
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// 初始化内存分配器
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var mem_arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
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defer mem_arena.deinit();
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const mem_allocator = mem_arena.allocator();
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// 初始化大顶堆
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var maxHeap = MaxHeap(i32){};
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try maxHeap.init(std.heap.page_allocator, &[_]i32{ 9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2 });
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defer maxHeap.deinit();
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std.debug.print("\n输入列表并建堆后\n", .{});
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try maxHeap.print(mem_allocator);
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// 获取堆顶元素
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var peek = maxHeap.peek();
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std.debug.print("\n堆顶元素为 {}\n", .{peek});
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// 元素入堆
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const val = 7;
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try maxHeap.push(val);
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std.debug.print("\n元素 {} 入堆后\n", .{val});
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try maxHeap.print(mem_allocator);
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// 堆顶元素出堆
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peek = try maxHeap.poll();
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std.debug.print("\n堆顶元素 {} 出堆后\n", .{peek});
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try maxHeap.print(mem_allocator);
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// 获取堆的大小
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var size = maxHeap.size();
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std.debug.print("\n堆元素数量为 {}", .{size});
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// 判断堆是否为空
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var isEmpty = maxHeap.isEmpty();
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std.debug.print("\n堆是否为空 {}\n", .{isEmpty});
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const getchar = try std.io.getStdIn().reader().readByte();
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_ = getchar;
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}
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@ -710,10 +710,10 @@ comments: true
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```go title="my_heap.go"
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/* 构造函数,根据切片建堆 */
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func newMaxHeap(nums []any) *maxHeap {
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// 所有元素入堆
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// 将列表元素原封不动添加进堆
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h := &maxHeap{data: nums}
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// 堆化除叶结点以外的其他所有结点
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for i := len(h.data) - 1; i >= 0; i-- {
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// 堆化除叶结点以外的其他所有结点
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h.siftDown(i)
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}
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return h
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@ -228,7 +228,7 @@ comments: true
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**稳定排序**:不交换相等元素。
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**自适排序**:引入 `flag` 优化后(见下文),最佳时间复杂度为 $O(N)$ 。
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**自适应排序**:引入 `flag` 优化后(见下文),最佳时间复杂度为 $O(N)$ 。
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## 效率优化
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