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]
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.
/**
* Definition for singly-linked list.
* function ListNode(val, next) {
* this.val = (val===undefined ? 0 : val)
* this.next = (next===undefined ? null : next)
* }
*/
/**
* @param {ListNode} l1
* @param {ListNode} l2
* @return {ListNode}
*/
var addTwoNumbers = function (l1, l2) {
let carry = 0; // determines the value to be carried when adding digits
let current = new ListNode(-1); // creates a new linked list with a head as -1
let head = current; // points to head of new linked list
while (l1 || l2 || carry) {
let l1Val = l1 ? l1.val : 0; // gets value from list1
let l2Val = l2 ? l2.val : 0; // gets value from list2
let nextDigit = (l1Val + l2Val + carry) % 10; // gets the right most digit of total
current.next = new ListNode(nextDigit); // adds the total as a new node in list
current = current.next; // points to newly created node
carry = Math.floor((l1Val + l2Val + carry) / 10); // resets carry value
l1 = l1 ? l1.next : null;
l2 = l2 ? l2.next : null;
}
return head.next;
};None