Solution: Add Two Numbers II

Statement

You are given two non empty singly linked lists l1 and l2 that represent two non negative integers. Each node stores a single digit in Node.val, and the digits are ordered from most significant to least significant.

Return the sum of the two numbers as a singly linked list in the same most significant to least significant digit order.

Note: Follow up: can you solve this without reversing the input lists?

Constraints:

• The number of nodes in each of l1 and l2 is in the range $[1, 100]$.

• $0 \leq$ ...