class Solution { public: vector<string> Permutation(string str) { vector<string> ans; if(str.length() == 0) return ans; permutation(ans,str,0); return ans; } void permutation(vector<string> &ans,string str,int index ){ if(index >= str.length()){ //找到了一个答案 //对于去除重复排列,还有一种非常简单...