Leetcode2---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.

Example

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

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} l1
 * @param {ListNode} l2
 * @return {ListNode}
 */
var addTwoNumbers = function(l1, l2) {
    // curry表示进位
    var curry = 0;
    var head = new ListNode(0);
    var res = head;
    
    while(l1 || l2) {
        var val1 = l1 ? l1.val : 0;
        var val2 = l2 ? l2.val : 0;
        l1 = l1 ? l1.next : null;
        l2 = l2 ? l2.next : null;
        
        var val = val1 + val2 + curry;
        curry = parseInt(val / 10);
        val = val % 10;

        var node = new ListNode(val);
        head.next = node;
        head = head.next;
    }
    if(curry > 0) {
        var node = new ListNode(curry);
        head.next = node;
    }
    return res.next;
};