题解 | #有重复项数字的全排列#

回溯

import java.util.*;

public class Solution {
   public ArrayList<ArrayList<Integer>> permuteUnique(int[] num) {
        ArrayList<ArrayList<Integer>> res = new ArrayList<>();
        Arrays.sort(num);
        boolean[] visited = new boolean[num.length];
        ArrayList<Integer> temp = new ArrayList<>();
        backTrack(num,temp,res,visited);
        return res;
    }

    public void backTrack(int[] num,ArrayList<Integer> temp,ArrayList<ArrayList<Integer>> res,boolean[] visited){
        if(temp.size() == num.length){
            res.add(new ArrayList<>(temp));
            return;
        }
        for(int i=0;i<num.length;i++){
            if((visited[i] == true) || (i>0 && num[i] == num[i-1] && !visited[i-1])){
                continue;
            }else{
                temp.add(num[i]);
                visited[i] = true;
                backTrack(num,temp,res,visited);
                temp.remove(temp.size()-1);
                visited[i] = false;
            }
        }
    }
}