2. Add Two Numbers

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 contain a single digit. Add the two numbers and return it as a linked list.

You may assume the two numbers do not contain any leading zero, except the number 0 itself.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)

Output: 7 -> 0 -> 8

 

 

 

1 /** 2  * Definition for singly-linked list. 3  * function ListNode(val) { 4  *     this.val = val; 5  *     this.next = null; 6  * } 7  */ 8 /** 9  * @param {ListNode} l110  * @param {ListNode} l211  * @return {ListNode}12  */13 var addTwoNumbers = function(l1, l2) {14     15     //这种累加的题目，主要是注意进位16     var carry = 0;17     //头指针18     var head = new ListNode(0);19 20     var res = head;21     22     //保证两个都有值 就累加，否者就直接添加23     while(l1&&l2){24         25         //一开始就加上carry,默认是026         var val = l1.val + l2.val + carry;27         val - 9 > 0 ? carry = 1 : carry = 0;28      29         val %= 10;  30         var node = new ListNode(val);31         res.next = node;32         33         res = node;34         35         l1 = l1.next;36         l2 = l2.next;37        38     }39     40     //处理 2->3->4 + 2->3 这种41     while(l1){42      43             var val = l1.val + carry;44             val - 9 > 0 ? carry = 1 : carry = 0;45             val %= 10;46             var node = new ListNode(val);47             res.next = node;48         49             res = node;50             l1 = l1.next;51      52     }53     54      while(l2){55      56             var val = l2.val + carry;57             val - 9 > 0 ? carry = 1 : carry = 0;58             val %= 10;59             var node = new ListNode(val);60             res.next = node;61         62             res = node;63             l2 = l2.next;64     }65     66     //注意处理最后一个进位  比如 5,5  输出0->167     if(carry){68            var node = new ListNode(carry);69             res.next = node;70 71             res = node;72     }73     74     return head.next;75     76     77 };