package algoexpert;

import java.util.ArrayList;

/*

PROBLEM:

[Integer or ArrayList<Object>] -> sum (based on formula)

[x,[y,z,[a]]] -> x + 2y + 2z + 3a

Logic:

go over the array

if int -> add to current Sum

else -> goDeeper(array, multiplier)

Solution:

1. Recursion : T : O(n) | S : O(n)

*/

public class ProductSum {

public static int goDeeper(ArrayList<Object> array, Integer multiplier)

{

int currentSum = 0;

for (Object consider : array){

if (consider instanceof Integer)

{

currentSum += ((Integer)consider * multiplier); // add to sum

}

else

{

// it is an arraylist -> go deeper

currentSum += multiplier * goDeeper((ArrayList<Object>)consider, multiplier + 1);

}

}

return currentSum;

}

public static int productSum(ArrayList<Object> array)

{

return goDeeper(array, 1);

}

}