题目：

题解：

class Solution:
    def readBinaryWatch(self, turnedOn: int) -> List[str]:
        ans = list()
        for i in range(1024):
            h, m = i >> 6, i & 0x3f   # 用位运算取出高 4 位和低 6 位
            if h < 12 and m < 60 and bin(i).count("1") == turnedOn:
                ans.append(f"{h}:{m:02d}")
        return ans