LeetCode-2. Add Two Numbers

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问题描述

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 :

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Input: l1 = [2,4,3], l2 = [5,6,4]
Output: [7,0,8]
Explanation: 342 + 465 = 807.

解答

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/*
 * @Description: 2. Add Two Numbers
 * @Author: libk
 * @Github: https://github.com/libk
 */
/**
 * 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}
 */
let addTwoNumbers = function(l1, l2) {
  let dummy = new ListNode()
  let cur = dummy
  let carry = 0

  while (l1 !== null || l2 !== null || 1 === carry) {
    let sum = 0

    if (l1 !== null) {
      sum += l1.val
      l1 = l1.next
    }
    if (l2 !== null) {
      sum += l2.val
      l2 = l2.next
    }
    sum += carry
    carry = Math.floor(sum / 10)
    let sumNode = new ListNode(sum % 10)
    cur.next = sumNode
    cur = cur.next
  }
  return dummy.next
}