class Solution {
    public List<List<Integer>> permute(int[] nums) {
        List<List<Integer>> result = new ArrayList<>();
        List<Integer> temp = new ArrayList<>();

        // to keep track if element is included in permutation or not
        boolean[] visited = new boolean[nums.length];
        findPermutations(nums, visited, result, temp);
        return result;
    }

    public void findPermutations(int[] nums, boolean[] visited, List<List<Integer>> result, List<Integer> temp)
    {
        // Base condition : when temp array becomes equal to actual size of array
        if(temp.size() == nums.length)
        {
            result.add(new ArrayList<>(temp));
            return;
        }

        for(int i=0; i<nums.length; i++)
        {
            if(visited[i] == false)
            {
                // solve: pick the current element if it's not added in permutation
                temp.add(nums[i]);
                visited[i] = true;

                // explore: calling recursively 
                findPermutations(nums, visited, result, temp);

                // backtrack: do not pick the element
                temp.remove(temp.size() - 1);
                visited[i] = false;
            }
        }
        return;
    }
}