package LeetCode;

import java.util.ArrayList;
import java.util.List;

public class LC_46 {
    static List<List<Integer>> res = new ArrayList<>();
    static ArrayList<Integer> path = new ArrayList<>();
    static ArrayList<Integer> used = new ArrayList<>();

    public static void main(String[] args) {
        int[] nums = {1, 2, 3};
        permute(nums);
    }

    public static List<List<Integer>> permute(int[] nums) {
        backtracking(nums);
        System.out.println(res);
        return res;
    }

    public static void backtracking(int[] nums) {
        if (path.size() == nums.length) {
            res.add(new ArrayList<>(path));
            return;
        }
        for (int i = 0; i < nums.length; i++) {
            if (!used.contains(nums[i])) {
                path.add(nums[i]);
                used.add(nums[i]);
            } else continue;
            backtracking(nums);
            used.remove(path.get(path.size()-1));
            path.remove(path.size() - 1);
        }
    }
}