Product Sum

Given an array (that can have nested arrays) - return the sum of all the numbers in the array. If nested array is encountered, recursively add the numbers in the nested array multiplied by the depth of the nested array.

Example

Input: [5, 2, [7, -1], 3, [6, [-13, 8], 4]]

Output: 12

Explanation

If we encounter a non nested value - we simply add it to the global sum. If we encounter a nested array, the sum inside of the nested array is multiplied with the depth of that array and then returned.

So the array [5, 2, [7, -1], 3, [6, [-13, 8], 4]] becomes:

Equation = (5 + 2 + (7 - 1) * 2 + 3 + (6 + (-13 + 8)*3 + 4)*2) * 1 = 12