401. Binary Watch【E】

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".

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首先就想到了位操作

注意超過12 和 60的都是壞數據

、

class Solution(object):
    def readBinaryWatch(self, num):

        if num > 9:
            return []
        res = []

        m = 0
        h = 0

        while h < 5 and h <= num:
            m = num - h
            if m > 6:
                h += 1
                continue
            #print h,m
            hl = (4-h)*['0'] + h*['1']
            ml = (6-m)*['0'] + m*['1']
            #print hl,ml

            hper = set(itertools.permutations(hl))
            mper = set(itertools.permutations(ml))

            hres = []
            mres = []
            for i in hper:
                t = ''.join(i)
                hres += int(t,2),
            for i in mper:
                t = ''.join(i)
                mres += int(t,2),
            mres.sort()
            hres.sort()

            for i in hres:
                if i > 11:
                    continue
                for j in mres:
                    if j >= 60:
                        continue
                    res += [i,j],
            h += 1

        res.sort()
        rres = []
        for i,j in res:
            ii = str(i)
            jj = str(j)
            if len(jj) < 2:
                jj = '0' + jj
            rres += ii + ':' + jj,   
        return rres

        """
        :type num: int
        :rtype: List[str]
        """