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Commit 230e9d9

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Merge pull request youngyangyang04#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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‎problems/0347.前K个高频元素.md‎

Lines changed: 80 additions & 77 deletions
Original file line numberDiff line numberDiff line change
@@ -268,99 +268,102 @@ func topKFrequent(nums []int, k int) []int {
268268

269269

270270

271-
javaScript:
271+
JavaScript:
272272
```js
273-
/**
274-
* @param{number[]}nums
275-
* @param{number}k
276-
* @return{number[]}
277-
*/
278-
vartopKFrequent=function(nums, k) {
279-
constmap=newMap();
280-
281-
for(constnumof nums) {
282-
map.set(num, (map.get(num) ||0) +1);
283-
}
273+
// js 没有堆 需要自己构造
274+
classHeap {
275+
constructor(compareFn) {
276+
this.compareFn= compareFn;
277+
this.queue= [];
278+
}
279+
280+
// 添加
281+
push(item) {
282+
// 推入元素
283+
this.queue.push(item);
284284

285-
// 创建小顶堆
286-
const priorityQueue = new PriorityQueue((a, b) => a[1] - b[1]);
285+
// 上浮
286+
let index = this.size() - 1; // 记录推入元素下标
287+
let parent = Math.floor((index - 1) / 2); // 记录父节点下标
287288

288-
// entry 是一个长度为2的数组,0位置存储key,1位置存储value
289-
for (const entry of map.entries()) {
290-
priorityQueue.push(entry);
291-
if (priorityQueue.size() > k) {
292-
priorityQueue.pop();
289+
while (parent >= 0 && this.compare(parent, index) > 0) { // 注意compare参数顺序
290+
[this.queue[index], this.queue[parent]] = [this.queue[parent], this.queue[index]];
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292+
// 更新下标
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index = parent;
294+
parent = Math.floor((index - 1) / 2);
295+
}
293296
}
294-
}
295297

296-
const ret = [];
298+
// 获取堆顶元素并移除
299+
pop() {
300+
// 堆顶元素
301+
const out = this.queue[0];
297302

298-
for(let i = priorityQueue.size() - 1; i >= 0; i--) {
299-
ret[i] = priorityQueue.pop()[0];
300-
}
303+
// 移除堆顶元素 填入最后一个元素
304+
this.queue[0] = this.queue.pop();
301305

302-
return ret;
303-
};
306+
// 下沉
307+
let index = 0; // 记录下沉元素下标
308+
let left = 1; // left 是左子节点下标 left + 1 则是右子节点下标
309+
let searchChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
304310

311+
while (searchChild !== undefined && this.compare(index, searchChild) > 0) { // 注意compare参数顺序
312+
[this.queue[index], this.queue[searchChild]] = [this.queue[searchChild], this.queue[index]];
305313

306-
function PriorityQueue(compareFn) {
307-
this.compareFn = compareFn;
308-
this.queue = [];
309-
}
314+
// 更新下标
315+
index = searchChild;
316+
left = 2 * index + 1;
317+
searchChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
318+
}
310319

311-
// 添加
312-
PriorityQueue.prototype.push = function(item) {
313-
this.queue.push(item);
314-
let index = this.queue.length - 1;
315-
let parent = Math.floor((index - 1) / 2);
316-
// 上浮
317-
while(parent >= 0 && this.compare(parent, index) > 0) {
318-
// 交换
319-
[this.queue[index], this.queue[parent]] = [this.queue[parent], this.queue[index]];
320-
index = parent;
321-
parent = Math.floor((index - 1) / 2);
322-
}
323-
}
320+
return out;
321+
}
324322

325-
// 获取堆顶元素并移除
326-
PriorityQueue.prototype.pop = function() {
327-
const ret = this.queue[0];
328-
329-
// 把最后一个节点移到堆顶
330-
this.queue[0] = this.queue.pop();
331-
332-
let index = 0;
333-
// 左子节点下标,left + 1 就是右子节点下标
334-
let left = 1;
335-
let selectedChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
336-
337-
// 下沉
338-
while(selectedChild !== undefined && this.compare(index, selectedChild) > 0) {
339-
// 交换
340-
[this.queue[index], this.queue[selectedChild]] = [this.queue[selectedChild], this.queue[index]];
341-
index = selectedChild;
342-
left = 2 * index + 1;
343-
selectedChild = this.compare(left, left + 1) > 0 ? left + 1 : left;
344-
}
323+
size() {
324+
return this.queue.length;
325+
}
345326

346-
return ret;
347-
}
327+
// 使用传入的 compareFn 比较两个位置的元素
328+
compare(index1, index2) {
329+
// 处理下标越界问题
330+
if (this.queue[index1] === undefined) return 1;
331+
if (this.queue[index2] === undefined) return -1;
332+
333+
return this.compareFn(this.queue[index1], this.queue[index2]);
334+
}
348335

349-
PriorityQueue.prototype.size = function() {
350-
return this.queue.length;
351336
}
352337

353-
// 使用传入的 compareFn 比较两个位置的元素
354-
PriorityQueue.prototype.compare = function(index1, index2) {
355-
if (this.queue[index1] === undefined) {
356-
return 1;
357-
}
358-
if (this.queue[index2] === undefined) {
359-
return -1;
360-
}
338+
const topKFrequent = function (nums, k) {
339+
const map = new Map();
361340

362-
return this.compareFn(this.queue[index1], this.queue[index2]);
363-
}
341+
for (const num of nums) {
342+
map.set(num, (map.get(num) || 0) + 1);
343+
}
344+
345+
// 创建小顶堆
346+
const heap= new Heap((a, b) => a[1] - b[1]);
347+
348+
// entry 是一个长度为2的数组,0位置存储key,1位置存储value
349+
for (const entry of map.entries()) {
350+
heap.push(entry);
351+
352+
if (heap.size() > k) {
353+
heap.pop();
354+
}
355+
}
356+
357+
// return heap.queue.map(e => e[0]);
358+
359+
const res = [];
360+
361+
for (let i = heap.size() - 1; i >= 0; i--) {
362+
res[i] = heap.pop()[0];
363+
}
364+
365+
return res;
366+
};
364367
```
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366369
TypeScript:

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