add-two-numbers.js

// Problem on LeetCode: https://leetcode.com/problems/add-two-numbers/

function addTwoNumbers(l1, l2) {
	let carry = 0;
	let p = l1;
	let q = l2;
	let dummyHead = new ListNode(0);
	let curr = dummyHead;
	while (p !== null || q !== null) {
		let x = p !== null ? p.val : 0;
		let y = q !== null ? q.val : 0;
		let sum = carry + x + y;
		carry = Math.floor(sum / 10);
		curr.next = new ListNode(sum % 10);
		curr = curr.next;
		if (p !== null) p = p.next;
		if (q !== null) q = q.next;
	}
	if (carry > 0) {
		curr.next = new ListNode(carry);
	}
	return dummyHead.next;
}