I have some code that prints out the summary of a given array but want to know how to print the position rather than the value inside the sum?

Question

import java.util.ArrayList;
import java.util.Arrays;

public class SumSet {

    static void sum_up_recursive(ArrayList<Integer> numbers, int target, ArrayList<Integer> partial) {
        int s = 0;
        for (int x : partial) {
            s += x;
        }
        if (s == target) {
            System.out.println("sum(" + Arrays.toString(partial.toArray()) + ")=" + target);
        }
        else if (s >= target) {
            return;
        }
        for (int i = 0; i < numbers.size(); i++) {
            ArrayList<Integer> remaining = new ArrayList<>();
            int n = numbers.get(i);
            for (int j = i + 1; j < numbers.size(); j++) {
                remaining.add(numbers.get(j));
            }
            ArrayList<Integer> partial_rec = new ArrayList<>(partial);
            partial_rec.add(n);
            sum_up_recursive(remaining, target, partial_rec);
        }
    }

    static void sum_up(ArrayList<Integer> numbers, int target) {
        sum_up_recursive(numbers, target, new ArrayList<>());
    }

    public static void main(String[] args) {
        Integer[] numbers = { 5, 5, 10, 15 };
        int target = 15;
        sum_up(new ArrayList<>(Arrays.asList(numbers)), target);
    }
}

The current output is:

sum([5, 10])=15
sum([5, 10])=15
sum([15])=15

I am trying to figure out how to get the output to print the position of the array:

sum([3]) = 15
sum([0,3)] = 15
sum([1,3)]=15

Answer 1

If I understand your question correctly you want to print the position in the original list, right?

In that case I'd suggest you use a custom element type, eg something like this:

class PositionalElement {
  final int position;
  final int value;

  public PositionalElement( int pos, int val ) {
    position = pos;
    value = val;
  }
}

and

int[] numbers = new int[] {5,5,10,15};
List<PositionalElement> elements = new ArrayList<>();
for( int i = 0; i < numbers.length; i++ ) {     
  elements.add( new PositionalElement( i, numbers[i] ) );
}

That way, when printing your output you're free to either use value and/or position of each element.