1. class Solution {
  2.     public List<List<Integer>> permute(int[] nums) {
  3.         List<List<Integer>> result = new ArrayList<>();
  4.         List<Integer> temp = new ArrayList<>();
  5.  
  6.         // to keep track if element is included in permutation or not
  7.         boolean[] visited = new boolean[nums.length];
  8.         findPermutations(nums, visited, result, temp);
  9.         return result;
  10.     }
  11.  
  12.     public void findPermutations(int[] nums, boolean[] visited, List<List<Integer>> result, List<Integer> temp)
  13.     {
  14.         // Base condition : when temp array becomes equal to actual size of array
  15.         if(temp.size() == nums.length)
  16.         {
  17.             result.add(new ArrayList<>(temp));
  18.             return;
  19.         }
  20.  
  21.         for(int i=0; i<nums.length; i++)
  22.         {
  23.             if(visited[i] == false)
  24.             {
  25.                 // solve: pick the current element if it's not added in permutation
  26.                 temp.add(nums[i]);
  27.                 visited[i] = true;
  28.  
  29.                 // explore: calling recursively 
  30.                 findPermutations(nums, visited, result, temp);
  31.  
  32.                 // backtrack: do not pick the element
  33.                 temp.remove(temp.size() - 1);
  34.                 visited[i] = false;
  35.             }
  36.         }
  37.         return;
  38.     }
  39. }