Description

You have two linked lists, they represent a number but backwards. You are supposed to add them together and return the sum of the two.

Add two backward linked lists :: Use long addition and carry the one

Runtime

O(n)

Pseudocode

While l1 or l2:
	add the two numbers + the prev 10s place
	save the 10s place
if the_one exists:
	add to end
return the resultant linked list