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7822bf9cd4
* Add top_k.c based on my_heap.c * Improve the implementation of top_k.js * Add a comment to top_k
40 lines
1.1 KiB
Java
40 lines
1.1 KiB
Java
/**
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* File: top_k.java
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* Created Time: 2023-06-12
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* Author: Krahets (krahets@163.com)
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*/
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package chapter_heap;
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import utils.*;
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import java.util.*;
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public class top_k {
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/* 基于堆查找数组中最大的 k 个元素 */
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static Queue<Integer> topKHeap(int[] nums, int k) {
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// 初始化小顶堆
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Queue<Integer> heap = new PriorityQueue<Integer>();
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// 将数组的前 k 个元素入堆
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for (int i = 0; i < k; i++) {
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heap.offer(nums[i]);
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}
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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 (int i = k; i < nums.length; i++) {
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// 若当前元素大于堆顶元素,则将堆顶元素出堆、当前元素入堆
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if (nums[i] > heap.peek()) {
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heap.poll();
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heap.offer(nums[i]);
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}
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}
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return heap;
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}
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public static void main(String[] args) {
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int[] nums = { 1, 7, 6, 3, 2 };
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int k = 3;
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Queue<Integer> res = topKHeap(nums, k);
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System.out.println("最大的 " + k + " 个元素为");
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PrintUtil.printHeap(res);
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}
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}
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