比较巧妙的做法
c++代码

class Solution {
public:
    vector<int> getLeastNumbers_Solution(vector<int> input, int k) {
        vector<int> C;
        int a = -1000;
        set<int> m;
        for (int i = 0 ; i < input.size() ; i ++)
        {
            m.insert(input[i]);
        }

        for (int i = 0 ; i < k ; i ++)
        {
            int s = (*(m.upper_bound(a)));
            C.push_back(s);
            a = s;
        }

        return C;
    }
};