Subset Sums

Given a list arr of n integers, return sums of all subsets in it. Output sums can be printed in any order.

Example 1:

Input:
n = 2
arr[] = {2, 3}
Output:
0 2 3 5
Explanation:
When no elements is taken then Sum = 0.
When only 2 is taken then Sum = 2.
When only 3 is taken then Sum = 3.
When element 2 and 3 are taken then 
Sum = 2+3 = 5.
Example 2:

Input:
n = 3
arr = {5, 2, 1}
Output:
0 1 2 3 5 6 7 8
Your Task:  
You don't need to read input or print anything. Your task is to complete the function subsetSums() which takes a list/vector and an integer n as an input parameter and returns the list/vector of all the subset sums.

Expected Time Complexity: O(2n)
Expected Auxiliary Space: O(2n)

Constraints:
1 <= n <= 15
0 <= arr[i] <= 104

solution :
Here we are using recursions and calling that taking a looop in string and asking whether it add the element to sum or not 
if yes:
sum+arr[i],i++
else:
sum,i++,

ater filling all places like 1,2,3 we went upto index 3 it is the final decision so at that time it added the sum of all substring to a ArrayList and finally we are sorting arrayList using collections and returning sorted arraylist

class Solution {
    void fun(int id,int sum,ArrayList<Integer> arr,int N,ArrayList<Integer> sumSubset){
        if(id == N){
            sumSubset.add(sum);
            return;
        }
        //if accepting
        fun(id+1,sum+arr.get(id),arr,N,sumSubset);
        //if not accepting
        fun(id+1,sum,arr,N,sumSubset);
    }
    ArrayList<Integer> subsetSums(ArrayList<Integer> arr, int n) {
        ArrayList<Integer> sumSubset = new ArrayList<>();
        fun(0,0,arr,n,sumSubset);
        Collections.sort(sumSubset);
        return sumSubset;
    }
}