Summing integers as arrays

Suppose you're given two arrays of length N, used to represent integer numbers. Each value in the represented integer is comma separated (ranging from 0-9) in the array. For example:

• 15 is represented as [1,5]
• 1200 is represented as [1,2,0,0]

Given this information, write a function that will sum the two arrays together for this representation. For example:

• [8,8] + [1] = [8,9]
• [9,5] + [1,6] = [1,1,1]