Permutations

LEETCODE PROBLEM SOLVING
PROBLEM->PERMUTATIONS
import java.util.*;

class Solution {
    public List<List<Integer>> permute(int[] nums) {
        List<List<Integer>> result = new ArrayList<>();
        backtrack(result, new ArrayList<>(), nums, new boolean[nums.length]);
        return result;
    }

    private void backtrack(List<List<Integer>> result,
                           List<Integer> temp,
                           int[] nums,
                           boolean[] used) {
        if (temp.size() == nums.length) {
            result.add(new ArrayList<>(temp));
            return;
        }

        for (int i = 0; i < nums.length; i++) {
            if (used[i]) continue;
            used[i] = true;
            temp.add(nums[i]);
            backtrack(result, temp, nums, used);
            used[i] = false;
            temp.remove(temp.size() - 1);
        }
    }
}