剑指offer python版 38.字符串的排列

"""
输入一个字符串，打印出该字符串中字符的所有排列。
如输入abc，则打印出abc、acb、bac、cab、cba
"""
class Solution:
    def Permutation(self, s):
        if s == None:
            return []
        if len(s) == 1:
            return list(s)

        else:
            result = []
            a = s[-1]
            for i in self.Permutation(s[:-1]):
                for j in range(len(i) + 1):
                    result.append(i[:j] + a + i[j:])
            result = list(set(result))
            result.sort()
            return result

    def Permutation1(self, ss):
        if not len(ss):
            return []
        if len(ss) == 1:
            return list(ss)

        charList = list(ss)
        charList.sort()
        pStr = []
        for i in range(len(charList)):
            if i > 0 and charList[i] == charList[i-1]:
                continue
            temp = self.Permutation1(''.join(charList[:i]) + ''.join(charList[i+1:]))
            for j in temp:
                pStr.append(charList[i] + j)
        return pStr

    # 扩展习题，生成字符的所有组合
    # 比如输入abc,则他们的组合有['a', 'ab', 'abc', 'ac',
    # 'b', 'bc', 'c'],ab和ba属于不同的排列但属于一个集合
    def group(self, ss):
        if not len(ss):
            return []
        if len(ss) == 1:
            return list(ss)
        charList = list(ss)
        charList.sort()
        pStr = []
        for i in range(len(charList)):
            pStr.append(charList[i])
            if i > 0 and charList[i] == charList[i-1]:
                continue
            temp = self.group(''.join(charList[i+1:]))
            for j in temp:
                pStr.append(charList[i] + j)
            pStr = list(set(pStr))
            pStr.sort()
        return pStr

if __name__ == '__main__':
    ss = 'abc'
    S = Solution()
    print(S.Permutation1(ss))
    print(S.group(ss))