Add Two Numbers
Difficulty: Medium
Category: DSA
Topics: Linked List, Math, Recursion
Asked at: Bloomberg, Microsoft, Amazon, Google, Facebook, Apple, Adobe, Paypal, Coupang, Oracle, Uber, VMware, Yahoo
You are given two **non-empty** linked lists representing two non-negative integers. The digits are stored in **reverse order**, and each of their nodes 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.
**Example 1:**
**Input:** l1 = [2,4,3], l2 = [5,6,4]
**Output:** [7,0,8]
**Explanation:** 342 + 465 = 807.
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**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]
```
**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.