Add TypeScript code and docs to Chapter of Heap (#349)
* Add TypeScript code and docs to Chapter of Heap * Update my_heap.ts --------- Co-authored-by: Yudong Jin <krahets@163.com>pull/358/head
Justin Tse
2 years ago
committed by
GitHub
parent
7666632d0c
commit
1cc9cecebe
@ -0,0 +1,160 @@
|
||||
/**
|
||||
* File: my_heap.js
|
||||
* Created Time: 2023-02-07
|
||||
* Author: Justin (xiefahit@gmail.com)
|
||||
*/
|
||||
|
||||
import { printHeap } from "../module/PrintUtil";
|
||||
|
||||
/* 最大堆类 */
|
||||
class MaxHeap {
|
||||
private maxHeap: number[];
|
||||
/* 构造函数，建立空堆或根据输入列表建堆 */
|
||||
constructor(nums?: number[]) {
|
||||
// 将列表元素原封不动添加进堆
|
||||
this.maxHeap = nums === undefined ? [] : [...nums];
|
||||
// 堆化除叶结点以外的其他所有结点
|
||||
for (let i = this.parent(this.size() - 1); i >= 0; i--) {
|
||||
this.siftDown(i);
|
||||
}
|
||||
}
|
||||
|
||||
/* 获取左子结点索引 */
|
||||
private left(i: number): number {
|
||||
return 2 * i + 1;
|
||||
}
|
||||
|
||||
/* 获取右子结点索引 */
|
||||
private right(i: number): number {
|
||||
return 2 * i + 2;
|
||||
}
|
||||
|
||||
/* 获取父结点索引 */
|
||||
private parent(i: number): number {
|
||||
return Math.floor((i - 1) / 2); // 向下整除
|
||||
}
|
||||
|
||||
/* 交换元素 */
|
||||
private swap(i: number, j: number): void {
|
||||
const a = this.maxHeap[i],
|
||||
b = this.maxHeap[j],
|
||||
tmp = a;
|
||||
this.maxHeap[i] = b;
|
||||
this.maxHeap[j] = tmp;
|
||||
}
|
||||
|
||||
/* 获取堆大小 */
|
||||
public size(): number {
|
||||
return this.maxHeap.length;
|
||||
}
|
||||
|
||||
/* 判断堆是否为空 */
|
||||
public isEmpty(): boolean {
|
||||
return this.size() === 0;
|
||||
}
|
||||
|
||||
/* 访问堆顶元素 */
|
||||
public peek(): number {
|
||||
return this.maxHeap[0];
|
||||
}
|
||||
|
||||
/* 元素入堆 */
|
||||
public push(val: number): void {
|
||||
// 添加结点
|
||||
this.maxHeap.push(val);
|
||||
// 从底至顶堆化
|
||||
this.siftUp(this.size() - 1);
|
||||
}
|
||||
|
||||
/* 从结点 i 开始，从底至顶堆化 */
|
||||
private siftUp(i: number): void {
|
||||
while (true) {
|
||||
// 获取结点 i 的父结点
|
||||
const p = this.parent(i);
|
||||
// 当“越过根结点”或“结点无需修复”时，结束堆化
|
||||
if (p < 0 || this.maxHeap[i] <= this.maxHeap[p]) break;
|
||||
// 交换两结点
|
||||
this.swap(i, p);
|
||||
// 循环向上堆化
|
||||
i = p;
|
||||
}
|
||||
}
|
||||
|
||||
/* 元素出堆 */
|
||||
public poll(): number {
|
||||
// 判空处理
|
||||
if (this.isEmpty()) throw new RangeError("Heap is empty.");
|
||||
// 交换根结点与最右叶结点（即交换首元素与尾元素）
|
||||
this.swap(0, this.size() - 1);
|
||||
// 删除结点
|
||||
const val = this.maxHeap.pop();
|
||||
// 从顶至底堆化
|
||||
this.siftDown(0);
|
||||
// 返回堆顶元素
|
||||
return val;
|
||||
}
|
||||
|
||||
/* 从结点 i 开始，从顶至底堆化 */
|
||||
private siftDown(i: number): void {
|
||||
while (true) {
|
||||
// 判断结点 i, l, r 中值最大的结点，记为 ma
|
||||
const l = this.left(i), r = this.right(i);
|
||||
let ma = i;
|
||||
if (l < this.size() && this.maxHeap[l] > this.maxHeap[ma]) ma = l;
|
||||
if (r < this.size() && this.maxHeap[r] > this.maxHeap[ma]) ma = r;
|
||||
// 若结点 i 最大或索引 l, r 越界，则无需继续堆化，跳出
|
||||
if (ma == i) break;
|
||||
// 交换两结点
|
||||
this.swap(i, ma);
|
||||
// 循环向下堆化
|
||||
i = ma;
|
||||
}
|
||||
}
|
||||
|
||||
/* 打印堆（二叉树） */
|
||||
public print(): void {
|
||||
printHeap(this.maxHeap);
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
function testPush(maxHeap: MaxHeap, val: number): void {
|
||||
maxHeap.push(val); // 元素入堆
|
||||
console.log(`\n添加元素 ${val} 后`);
|
||||
maxHeap.print();
|
||||
}
|
||||
|
||||
function testPoll(maxHeap: MaxHeap): void {
|
||||
const val = maxHeap.poll(); // 堆顶元素出堆
|
||||
console.log(`\n出堆元素为 ${val}`);
|
||||
maxHeap.print();
|
||||
}
|
||||
|
||||
/* Driver Code */
|
||||
/* 初始化大顶堆 */
|
||||
const maxHeap = new MaxHeap([9, 8, 6, 6, 7, 5, 2, 1, 4, 3, 6, 2]);
|
||||
console.log("\n输入列表并建堆后");
|
||||
maxHeap.print();
|
||||
|
||||
/* 获取堆顶元素 */
|
||||
let peek = maxHeap.peek();
|
||||
console.log(`\n堆顶元素为 ${peek}`);
|
||||
|
||||
/* 元素入堆 */
|
||||
const val = 7;
|
||||
maxHeap.push(val);
|
||||
console.log(`\n元素 ${val} 入堆后`);
|
||||
maxHeap.print();
|
||||
|
||||
/* 堆顶元素出堆 */
|
||||
peek = maxHeap.poll();
|
||||
console.log(`\n堆顶元素 ${peek} 出堆后`);
|
||||
maxHeap.print();
|
||||
|
||||
/* 获取堆大小 */
|
||||
const size = maxHeap.size();
|
||||
console.log(`\n堆元素数量为 ${size}`);
|
||||
|
||||
/* 判断堆是否为空 */
|
||||
const isEmpty = maxHeap.isEmpty();
|
||||
console.log(`\n堆是否为空 ${isEmpty}`);
|
||||
Loading…
Reference in new issue