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

problems/0347.前K个高频元素.md

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