Subset Sums

 Given a array arr of integers, return the sums of all subsets in the list.  Return the sums in any order.


Examples:


Input: arr[] = [2, 3]

Output: [0, 2, 3, 5]

Explanation: When no elements are taken then Sum = 0. When only 2 is taken then Sum = 2. When only 3 is taken then Sum = 3. When elements 2 and 3 are taken then Sum = 2+3 = 5.

Input: arr[] = [1, 2, 1]

Output: [0, 1, 1, 2, 2, 3, 3, 4]

Explanation: The possible subset sums are 0 (no elements), 1 (either of the 1's), 2 (the element 2), and their combinations.

Input: arr[] = [5, 6, 7]

Output: [0, 5, 6, 7, 11, 12, 13, 18]

Explanation: The possible subset sums are 0 (no elements), 5, 6, 7, and their combinations.


class Solution {

  

    public ArrayList<Integer> subsetSums(int[] arr) {

        // code here

          //List<List<Integer>> result= new ArrayList<>();


         ArrayList<Integer> result = new ArrayList<>();

        backtrack(arr, 0, result, 0);

        return result;

    }

    

   private void backtrack(int[] nums, int start, ArrayList<Integer> result, int sum)


{

  if (start == nums.length) {

            result.add(sum);

            return;

        }

        

 // Include nums[start]

        backtrack(nums, start + 1, result, sum + nums[start]);


        // Exclude nums[start]

        backtrack(nums, start + 1, result, sum);


    }

}

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