you have two numbers repsented by a linked list where each node contains a single digit. the digits are stored in reverse order such that the ones are at the head.write a function that sums the two numbers and returns the result as a linked list.
Repeat in forward order.
Just simply build list by putting % 10 in current, and carrying over to the next digit.
IF in forward order, we must add padding, and then add numbers to head instead of tail