2-add-two-numbers.js

/*
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]
*/
/**
 * 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 dummyHead = new ListNode(0);
  let carry = 0;
  let p = l1,
    q = l2;
  let curr = dummyHead;
  console.log(curr);
  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;
};