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39 lines
1.1 KiB
39 lines
1.1 KiB
6 months ago
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/**
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* File: top_k.cpp
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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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#include "../utils/common.hpp"
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/* Using heap to find the largest k elements in an array */
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priority_queue<int, vector<int>, greater<int>> topKHeap(vector<int> &nums, int k) {
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// Initialize min-heap
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priority_queue<int, vector<int>, greater<int>> heap;
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// Enter the first k elements of the array into the heap
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for (int i = 0; i < k; i++) {
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heap.push(nums[i]);
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}
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// From the k+1th element, keep the heap length as k
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for (int i = k; i < nums.size(); i++) {
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// If the current element is larger than the heap top element, remove the heap top element and enter the current element into the heap
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if (nums[i] > heap.top()) {
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heap.pop();
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heap.push(nums[i]);
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}
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}
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return heap;
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}
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// Driver Code
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int main() {
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vector<int> nums = {1, 7, 6, 3, 2};
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int k = 3;
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priority_queue<int, vector<int>, greater<int>> res = topKHeap(nums, k);
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cout << "The largest " << k << " elements are:";
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printHeap(res);
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return 0;
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}
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