题目
A binary watch has 4 LEDs on the top which represent the hours (0-11), and the 6 LEDs on the bottom represent the minutes (0-59).
Each LED represents a zero or one, with the least significant bit on the right.
For example, the above binary watch reads "3:25".
Given a non-negative integer n which represents the number of LEDs that are currently on, return all possible times the watch could represent.
Example:
Input: n = 1
Return: ["1:00", "2:00", "4:00", "8:00", "0:01", "0:02", "0:04", "0:08", "0:16", "0:32"]
Note:
- The order of output does not matter.
- The hour must not contain a leading zero, for example "01:00" is not valid, it should be "1:00".
- The minute must be consist of two digits and may contain a leading zero, for example "10:2" is not valid, it should be "10:02".
难度
Easy
方法
遍历所有可能的时间，如果其中1的个数等于n，则将该时间加入返回的结果列表中
python代码
class Solution(object):
def readBinaryWatch(self, num):
"""
:type num: int
:rtype: List[str]
"""
result = []
for i in range(12):
for j in range(60):
if bin(i).count("1") + bin(j).count("1") == num:
result.append("%d:%02d" % (i, j))
return result
assert Solution().readBinaryWatch(1) == ["0:01", "0:02", "0:04", "0:08", "0:16", "0:32", "1:00", "2:00", "4:00", "8:00"]
