题目：

题解：

class Solution {public List<String> readBinaryWatch(int turnedOn) {List<String> ans = new ArrayList<String>();for (int i = 0; i < 1024; ++i) {int h = i >> 6, m = i & 63; // 用位运算取出高 4 位和低 6 位if (h < 12 && m < 60 && Integer.bitCount(i) == turnedOn) {ans.add(h + ":" + (m < 10 ? "0" : "") + m);}}return ans;}
}