给定两个链表表示的非负整数，每个节点存储一位数，各位数以逆序存储。将两个数相加，以链表形式返回结果。

例如：

输入：(2 -> 4 -> 3) + (5 -> 6 -> 4)

输出：7 -> 0 -> 8

/**

* Definition for singly-linked list.

* public class ListNode {

* int val;

* ListNode next;

* ListNode(int x) { val = x; }

* }

*/

public class Solution {

public static ListNode addTwoNumbers(ListNode l1, ListNode l2) {

ListNode h = null;

ListNode p = null;

int carry = 0;

while (l1 != null || l2 != null) {

int v = (l1 != null ? l1.val : 0) + (l2 != null ? l2.val : 0) + carry;

ListNode n = new ListNode(v % 10);

carry = v / 10;

if (h == null) {

h = n;

p = h;

} else {

p.next = n;

p = n;

}

if (l1 != null) {

l1 = l1.next;

}

if (l2 != null) {

l2 = l2.next;

}

}

if (carry != 0) {

p.next = new ListNode(1);

}

return h;

}

}