Problem 145. Increment a number, given its digits

Take as input an array of digits (e.g. x = [1 2 3]) and output an array of digits that is that number "incremented" properly, (in this case, y = [1 2 4]).

Examples of proper input/output:

x = [1 9 1 9] ----> y = [1 9 2 0]

and

x = [9 9 9] ----> y = [1 0 0 0]