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Chandrasekar Gokulanathan

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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.
``````

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]
``````

Solution

``````/**
* @param {ListNode} l1
* @param {ListNode} l2
* @return {ListNode}
*/
var addTwoNumbers = function(l1, l2) {
let node = null;
const carry = arguments[2];

if (l1 || l2) {
if (!l1) {
l1 = new ListNode();
}
if (!l2) {
l2 = new ListNode();
}
let val = l1.val + l2.val;
if (carry) {
val += 1;
}
node = new ListNode(val %10, null);
node.next = addTwoNumbers(l1.next, l2.next, val > 9 ? 1 : 0);
} else if (carry) {
node = new ListNode(1, null);
}
return node;
};
``````