2.两数相加.js

/*
 * @lc app=leetcode.cn id=2 lang=javascript
 *
 * [2] 两数相加
 */


// @lc code=start
/**
 * 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) {
  // [99]
  // [99]
  // 进位
  // 89
  let addOne = 0
  let flag = cur = new ListNode(0)
  while(addOne || l1||l2){
    let val1 = l1!==null ? l1.val :0
    let val2 = l2!==null ? l2.val :0
    let sum = val1+val2 + addOne
    addOne = sum>=10 ? 1 : 0

    cur.next = new ListNode(sum%10)
    cur = cur.next
    if(l1){
      l1 = l1.next
    }
    if(l2){
      l2 = l2.next
    }
  }
  return flag.next

};
// @lc code=end