题解 | #有重复项数字的全排列#

代码优化空间很大

import java.util.*;

public class Solution {

    public ArrayList<ArrayList<Integer>> permuteUnique(int[] num) {
        permute1(num,0);
        return new ArrayList<>(set);
    }

    public void permute1(int[] num,int i) {
        if(i==num.length){
            ArrayList<Integer> integers = new ArrayList<>();
            for (int i1 : num) {
                integers.add(i1);
            }
            set.add(integers);
            return;
        }
        for (int j = i; j < num.length; j++) {
            swap(num,j,i);
            permute1(num,i+1);
            swap(num,j,i);
        }
    }

    public void swap(int[] arr,int s,int e){
        int temp = arr[s];
        arr[s] = arr[e];
        arr[e] = temp;
    }

    TreeSet<ArrayList<Integer>> set = new TreeSet<>((a1,a2)->{
        int i = 0;
        while(i<a1.size()){
            if(a1.get(i).compareTo(a2.get(i))!=0){
                return a1.get(i).compareTo(a2.get(i));
            }else{
                i++;
            }
        }
        return 0;
    });
}