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35 lines
1.1 KiB
35 lines
1.1 KiB
/**
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* File: top_k.js
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* Created Time: 2023-08-13
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* Author: Justin (xiefahit@gmail.com)
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*/
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const { MaxHeap } = require('./my_heap');
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/* 基于堆查找数组中最大的 k 个元素 */
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function topKHeap(nums, k) {
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// 使用大顶堆 MaxHeap ，对数组 nums 取相反数
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const invertedNums = nums.map((num) => -num);
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// 将数组的前 k 个元素入堆
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const heap = new MaxHeap(invertedNums.slice(0, k));
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// 从第 k+1 个元素开始，保持堆的长度为 k
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for (let i = k; i < invertedNums.length; i++) {
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// 若当前元素小于堆顶元素，则将堆顶元素出堆、当前元素入堆
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if (invertedNums[i] < heap.peek()) {
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heap.pop();
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heap.push(invertedNums[i]);
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}
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}
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// 取出堆中元素
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const maxHeap = heap.getMaxHeap();
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// 对堆中元素取相反数
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const invertedMaxHeap = maxHeap.map((num) => -num);
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return invertedMaxHeap;
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}
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/* Driver Code */
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const nums = [1, 7, 6, 3, 2];
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const k = 3;
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const res = topKHeap(nums, k);
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console.log(`最大的 ${k} 个元素为`, res);
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