Solution.cpp

class Solution {
public:
    vector<string> readBinaryWatch(int turnedOn) {
        vector<string> ans;
        for (int i = 0; i < 12; ++i) {
            for (int j = 0; j < 60; ++j) {
                if (__builtin_popcount(i) + __builtin_popcount(j) == turnedOn) {
                    ans.push_back(to_string(i) + ":" + (j < 10 ? "0" : "") + to_string(j));
                }
            }
        }
        return ans;
    }
};