sum-of-nodes.js

/*
2. Add Two Numbers
Solved
Medium
Topics
Companies

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]

*/

var addTwoNumbers = function (l1, l2) {
	function hasTensPlace(number) {
		return number >= 10;
	}

	function getUnitsPlace(number) {
		return number % 10;
	}

	let dummyNode = new ListNode(-1);
	let ans = dummyNode;

	let carry = 0;

	while (l1 || l2 || carry) {
		let sum = (l1 ? l1.val : 0) + (l2 ? l2.val : 0) + carry;

		carry = hasTensPlace(sum) ? 1 : 0;

		ans.next = new ListNode(getUnitsPlace(sum));
		ans = ans.next;
		if (l1) l1 = l1.next;
		if (l2) l2 = l2.next;
	}

	return dummyNode.next;
};