class Solution {
    public List<String> readBinaryWatch(int num) {
        List<String> times = new ArrayList<>();
        for (int h = 0; h < 12; h++)
            for (int m = 0; m < 60; m++)
                if (Integer.bitCount(h * 64 + m) == num)
                    times.add(String.format("%d:%02d", h, m));
        return times; 
    }
}