题解 | #字符串的排列#

from enum import unique
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param str string字符串 
# @return string字符串一维数组
#
class Solution:
    def Permutation(self , str: str) -> List[str]:
        # write code here
        n = len(str)
        if n == 0:
            return [""]
        if n == 1:
            return [str]
        if n == 2:
            if str != str[::-1]:
                return [str, str[::-1]]
            else:
                return [str]
        res = []
        flags = {}
        for i in range(n):
            if str[i] not in flags.keys():
                flags[str[i]] = 1
                temp = [str[j] for j in range(n) if j != i]
                ss = ''.join(temp)
                res.extend([str[i]+p for p in self.Permutation(ss)])
        return res