import java.util.ArrayList;

import java.util.List;

import java.util.Stack;

public class Permute {

private List<List<Integer>> res = new ArrayList<>();

public List<List<Integer>> permute(int[] nums) {

findPermute(nums, new Stack<>());

return res;

}

public void findPermute(int[] nums, Stack<Integer> stack) {

if (stack.size() == nums.length) {

res.add(stack);

return;

}

for (int i = 0; i < nums.length; i++) {

if (stack.contains(nums[i])) {

continue;

}

stack.push(nums[i]);

findPermute(nums, stack);

stack.pop();

}

}

}