Add Two Numbers

Add Two Numbers

You are given two non-empty linked lists representing two non-negative integers. The digits are stored in reverse order, and each node contains a single digit. Add the two numbers and return the sum as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Examples

Example 1:

Input: l1 = [2, 4, 3], l2 = [5, 6, 4]
Output: [7, 0, 8]
Explanation: 342 + 465 = 807

Example 2:

Input: l1 = [0], l2 = [0]
Output: [0]

Example 3:

Input: l1 = [9, 9, 9, 9, 9, 9, 9], l2 = [9, 9, 9, 9]
Output: [8, 9, 9, 9, 0, 0, 0, 1]
Explanation: 9999999 + 9999 = 10009998

Constraints

• The number of nodes in each linked list is in the range [1, 100].
• 0 <= Node.val <= 9
• It is guaranteed that the list represents a number that does not have leading zeros.

Expected Complexity

• Time: O(max(n, m)) where n and m are the lengths of the two lists
• Space: O(max(n, m)) for the result list