机试刷题_面试题 08.08. 有重复字符串的排列组合【python】

面试题 08.08. 有重复字符串的排列组合

class Solution:
    def backtrack(self,res,state,choices,selected):
        if len(state)==len(choices):
            res.append("".join(list(state)))
            return 
        duplicated = set()
        for i,choice in enumerate(choices):
            if choice not in duplicated and not selected[i]:
                duplicated.add(choice)
                selected[i] = True
                state.append(choice)
                self.backtrack(res,state,choices,selected)
                selected[i] = False
                state.pop()


    def permutation(self, S: str) -> List[str]:
        res = []
        self.backtrack(res,state=[],choices=list(S),selected=[False]*len(S))
        return res