每天刷一道牛客题霸-第12天-字符串的排列

题目

https://www.nowcoder.com/practice/fe6b651b66ae47d7acce78ffdd9a96c7?tpId=190&rp=1&ru=%2Fta%2Fjob-code-high-rd&qru=%2Fta%2Fjob-code-high-rd%2Fquestion-ranking

import java.util.*;
public class Solution {
    public ArrayList<String> list=new ArrayList<>();
    public ArrayList<String> Permutation(String str) {
        if(str.length()==1)
        {
            list.add(String.valueOf(str));
            return list;
        }
       if(str.length()!=0)
       {
           getAllString(str.toCharArray(),0);
       }
        Collections.sort(list);
        return list;
    }
    public void getAllString(char[] str,int index)
    {
        if(str.length-1<=index)
        {
            String str1=String.valueOf(str);
            if(!list.contains(str1))
            {
                list.add(str1);
            }
        }
         else
         {
            for(int i = index;i<str.length;i++)
            {
                swap(str,i,index);
                getAllString(str,index+1);
                swap(str,i,index);
            }
         }


    }
    public void swap(char[] str,int i ,int j)
    {
        char temp=str[i];
        str[i]=str[j];
        str[j]=temp;
    }
}