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Merge pull request #1600 from Jamcy123/347.前K个高频元素
347.前K个高频元素 JavaScript版本修改 原版JS代码无法提交报错
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程序员Carl
@ -268,99 +268,102 @@ func topKFrequent(nums []int, k int) []int {
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javaScript:
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JavaScript:
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```js
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/**
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* @param {number[]} nums
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* @param {number} k
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* @return {number[]}
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*/
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var topKFrequent = function(nums, k) {
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const map = new Map();
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for(const num of nums) {
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map.set(num, (map.get(num) || 0) + 1);
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}
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// 创建小顶堆
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const priorityQueue = new PriorityQueue((a, b) => a[1] - b[1]);
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// entry 是一个长度为2的数组，0位置存储key，1位置存储value
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for (const entry of map.entries()) {
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priorityQueue.push(entry);
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if (priorityQueue.size() > k) {
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priorityQueue.pop();
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// js 没有堆 需要自己构造
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class Heap {
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constructor(compareFn) {
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this.compareFn = compareFn;
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this.queue = [];
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}
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}
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const ret = [];
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// 添加
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push(item) {
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// 推入元素
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this.queue.push(item);
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for(let i = priorityQueue.size() - 1; i >= 0; i--) {
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ret[i] = priorityQueue.pop()[0];
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}
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// 上浮
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let index = this.size() - 1; // 记录推入元素下标
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let parent = Math.floor((index - 1) / 2); // 记录父节点下标
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return ret;
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while (parent >= 0 && this.compare(parent, index) > 0) { // 注意compare参数顺序
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[this.queue[index], this.queue[parent]] = [this.queue[parent], this.queue[index]];
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// 更新下标
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index = parent;
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parent = Math.floor((index - 1) / 2);
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}
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}
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// 获取堆顶元素并移除
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pop() {
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// 堆顶元素
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const out = this.queue[0];
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// 移除堆顶元素 填入最后一个元素
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this.queue[0] = this.queue.pop();
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// 下沉
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let index = 0; // 记录下沉元素下标
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let left = 1; // left 是左子节点下标 left + 1 则是右子节点下标
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let searchChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
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while (searchChild !== undefined && this.compare(index, searchChild) > 0) { // 注意compare参数顺序
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[this.queue[index], this.queue[searchChild]] = [this.queue[searchChild], this.queue[index]];
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// 更新下标
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index = searchChild;
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left = 2 * index + 1;
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searchChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
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}
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return out;
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}
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size() {
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return this.queue.length;
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}
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// 使用传入的 compareFn 比较两个位置的元素
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compare(index1, index2) {
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// 处理下标越界问题
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if (this.queue[index1] === undefined) return 1;
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if (this.queue[index2] === undefined) return -1;
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return this.compareFn(this.queue[index1], this.queue[index2]);
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}
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}
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const topKFrequent = function (nums, k) {
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const map = new Map();
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for (const num of nums) {
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map.set(num, (map.get(num) || 0) + 1);
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}
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// 创建小顶堆
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const heap= new Heap((a, b) => a[1] - b[1]);
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// entry 是一个长度为2的数组，0位置存储key，1位置存储value
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for (const entry of map.entries()) {
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heap.push(entry);
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if (heap.size() > k) {
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heap.pop();
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}
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}
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// return heap.queue.map(e => e[0]);
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const res = [];
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for (let i = heap.size() - 1; i >= 0; i--) {
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res[i] = heap.pop()[0];
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}
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return res;
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};
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function PriorityQueue(compareFn) {
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this.compareFn = compareFn;
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this.queue = [];
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}
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// 添加
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PriorityQueue.prototype.push = function(item) {
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this.queue.push(item);
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let index = this.queue.length - 1;
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let parent = Math.floor((index - 1) / 2);
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// 上浮
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while(parent >= 0 && this.compare(parent, index) > 0) {
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// 交换
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[this.queue[index], this.queue[parent]] = [this.queue[parent], this.queue[index]];
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index = parent;
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parent = Math.floor((index - 1) / 2);
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}
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}
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// 获取堆顶元素并移除
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PriorityQueue.prototype.pop = function() {
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const ret = this.queue[0];
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// 把最后一个节点移到堆顶
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this.queue[0] = this.queue.pop();
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let index = 0;
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// 左子节点下标，left + 1 就是右子节点下标
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let left = 1;
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let selectedChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
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// 下沉
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while(selectedChild !== undefined && this.compare(index, selectedChild) > 0) {
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// 交换
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[this.queue[index], this.queue[selectedChild]] = [this.queue[selectedChild], this.queue[index]];
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index = selectedChild;
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left = 2 * index + 1;
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selectedChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
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}
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return ret;
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}
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PriorityQueue.prototype.size = function() {
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return this.queue.length;
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}
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// 使用传入的 compareFn 比较两个位置的元素
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PriorityQueue.prototype.compare = function(index1, index2) {
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if (this.queue[index1] === undefined) {
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return 1;
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}
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if (this.queue[index2] === undefined) {
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return -1;
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}
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return this.compareFn(this.queue[index1], this.queue[index2]);
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}
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```
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TypeScript：
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