题解 | 字符串的排列

import java.util.*;


public class Solution {
    /**
     * 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ArrayList
     */
    public ArrayList<String> Permutation (String str) {
        // write code here
        ArrayList<String> arr = dfs(str,new boolean[str.length()],new String(""),
        new  ArrayList<String>());
       LinkedHashSet<String> set= new LinkedHashSet<String>();
       for(int i=0;i<arr.size();i++){
          set.add(arr.get(i));
       }

        return new ArrayList<String>(set);
    }
    public static ArrayList<String> dfs(String str,boolean[] visted,
    String stack,ArrayList<String> list){
        if(str.length()==stack.length()){
          String out=stack.substring(0);
           list.add(out);
           return list;
        }
        for(int i=0;i<str.length();i++){
            if(!visted[i]){
                stack+=str.charAt(i);
                visted[i]=true;
                dfs(str,visted,stack,list);
                visted[i]=false;
                stack=stack.substring(0,stack.length()-1);
            }
        }
        return list;
    }

}

字符串去重用linkedhashset