Kth Largest Element in an Array

Desicription

Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.

Example 1:

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Input: [3,2,1,5,6,4] and k = 2
Output: 5

Example 2:

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Input: [3,2,3,1,2,4,5,5,6] and k = 4
Output: 4

Note:

You may assume k is always valid, 1 ≤ k ≤ array’s length.

Solution

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class Solution {
public:
    int findKthLargest(vector<int>& nums, int k) {
        auto compare = [](int a, int b) {return a > b;};
        priority_queue<int, vector<int>, decltype(compare)> pq(compare);
        for(const auto& num : nums) {
            pq.push(num);
            while(pq.size() > k) {
                pq.pop();
            }
        }
        return pq.top();
    }
};