【劍指offer】面試題40.最小的k個數

解題思路

維護一個k大小的大頂堆，如果當前堆的size>k，則彈出

代碼

class Solution
{
public:
	vector<int> getLeastNumbers(vector<int>& arr, int k)
	{
		priority_queue<int, vector<int>, less<int>> q;//大頂堆
        //priority_queue<int, vector<int>, greater<int>> q;//小頂堆
		for (vector<int>::iterator it = arr.begin(); it != arr.end(); it++)
		{
		    q.push(*it);//堆的size<=k，則加入到堆中
			if(q.size()>k) q.pop();
		}
		vector<int> res;
		while (!q.empty())
		{
			res.push_back(q.top());
			q.pop();
		}
		return res;
	}
};