You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
39 lines
1.1 KiB
39 lines
1.1 KiB
/**
|
|
* File: top_k.cpp
|
|
* Created Time: 2023-06-12
|
|
* Author: krahets (krahets@163.com)
|
|
*/
|
|
|
|
#include "../utils/common.hpp"
|
|
|
|
/* Using heap to find the largest k elements in an array */
|
|
priority_queue<int, vector<int>, greater<int>> topKHeap(vector<int> &nums, int k) {
|
|
// Initialize min-heap
|
|
priority_queue<int, vector<int>, greater<int>> heap;
|
|
// Enter the first k elements of the array into the heap
|
|
for (int i = 0; i < k; i++) {
|
|
heap.push(nums[i]);
|
|
}
|
|
// From the k+1th element, keep the heap length as k
|
|
for (int i = k; i < nums.size(); i++) {
|
|
// If the current element is larger than the heap top element, remove the heap top element and enter the current element into the heap
|
|
if (nums[i] > heap.top()) {
|
|
heap.pop();
|
|
heap.push(nums[i]);
|
|
}
|
|
}
|
|
return heap;
|
|
}
|
|
|
|
// Driver Code
|
|
int main() {
|
|
vector<int> nums = {1, 7, 6, 3, 2};
|
|
int k = 3;
|
|
|
|
priority_queue<int, vector<int>, greater<int>> res = topKHeap(nums, k);
|
|
cout << "The largest " << k << " elements are:";
|
|
printHeap(res);
|
|
|
|
return 0;
|
|
}
|