题解 | #字符串的排列#

群排列算法加一个集合查重

import java.util.*;
public class Solution {
    ArrayList<String> we = new ArrayList<>();
    Set<String> you = new HashSet<>();
    public ArrayList<String> Permutation(String str) {
        String[] list = str.split("");
        quanpailie(list, 0);
       return we;
    }
    public void quanpailie(String[] list,int index){
        String sp;
        if(index == list.length){
            String t ="";
            for(String i : list){
t=t+i;}
            if(you.add(t)){
                we.add(t);
            }
        }else{
            for(int i =0;i<list.length;i++){
                sp = list[i];
                list[i] = list[index];
                list[index] = sp;
                quanpailie( list, index+1);
                sp = list[i];
                list[i] = list[index];
                list[index] = sp;
            }
        }
    }
}