最小的K个数

class Solution {
public:
    vector<int> GetLeastNumbers_Solution(vector<int> input, int k) {
        vector<int> res;
        if(input.size()<k||k<1)
            return res;
        if(input.size()==k)
            return input;
        multiset<int,greater<int>>  max;
        multiset<int,greater<int>>::iterator it;
        for(int i=0;i<input.size();i++)
            {
            if(max.size()<k)
                max.insert(input[i]);
            else
            {
                it=max.begin();
                if(input[i]<(*it))
                   {
                    max.erase(*it);
                    max.insert(input[i]);
                }
            }
        }
        it=max.begin();
        while(it!=max.end())
            {
            res.push_back(*it);
            it++;
        }
        return res;
    }
    
};