class Solution {
public:
    vector<string> readBinaryWatch(int num) {
        vector<string> res;
        //直接遍历  0:00 -> 12:00   每个时间有多少1
        for (int i = 0; i < 12; i++) {
            for (int j = 0; j < 60; j++) {
                if (count1(i) + count1(j) == num) {
                    res.push_back(to_string(i)+":"+
                                  (j < 10 ? "0"+to_string(j) : to_string(j)));
                }
            }
        }
        return res;
    }
    //计算二进制中1的个数
    int count1(int n) {
        int res = 0;
        while (n != 0) {
            n = n & (n - 1);
            res++;
        }
        return res;
    }
};