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38 lines
1.1 KiB
38 lines
1.1 KiB
/**
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* File: top_k.cs
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* Created Time: 2023-06-14
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* Author: hpstory (hpstory1024@163.com)
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*/
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namespace hello_algo.chapter_heap;
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public class top_k {
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/* 基於堆積查詢陣列中最大的 k 個元素 */
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PriorityQueue<int, int> TopKHeap(int[] nums, int k) {
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// 初始化小頂堆積
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PriorityQueue<int, int> heap = new();
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// 將陣列的前 k 個元素入堆積
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for (int i = 0; i < k; i++) {
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heap.Enqueue(nums[i], nums[i]);
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}
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// 從第 k+1 個元素開始，保持堆積的長度為 k
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for (int i = k; i < nums.Length; i++) {
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// 若當前元素大於堆積頂元素，則將堆積頂元素出堆積、當前元素入堆積
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if (nums[i] > heap.Peek()) {
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heap.Dequeue();
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heap.Enqueue(nums[i], nums[i]);
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}
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}
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return heap;
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}
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[Test]
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public void Test() {
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int[] nums = [1, 7, 6, 3, 2];
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int k = 3;
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PriorityQueue<int, int> res = TopKHeap(nums, k);
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Console.WriteLine("最大的 " + k + " 個元素為");
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PrintUtil.PrintHeap(res);
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}
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}
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