## 刷题内容

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.

#### Example:

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.


## 解题方案

/**
* function ListNode(val) {
*     this.val = val;
*     this.next = null;
* }
*/
/**
* @param {ListNode} l1
* @param {ListNode} l2
* @return {ListNode}
*/
let addTwoNumbers = function (l1,l2) {
let result = new ListNode(0),
node = result;
while(l1 || l2){
let r = node.val,
i = (l1 && l1.val) || 0,
j = (l2 && l2.val) || 0,
sum = r + i + j,
m,n;
if(sum >= 10){
m = 1;
n = sum - 10;
}else{
m = 0;
n = sum;
}
l1 = l1 && l1.next;
l2 = l2 && l2.next;
node.val = n;
if(m || l1 || l2){
node.next = new ListNode(m);
node = node.next
}
}
return result;
};

function ListNode(val) {
this.val = val;
this.next = null;
}