[leetcode]Add Two Numbers

You are given two linked lists representing two non-negative numbers. 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.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)

Output: 7 -> 0 -> 8

/** * Definition for singly-linked list. * public class ListNode { *     int val; *     ListNode next; *     ListNode(int x) { val = x; } * } */public class Solution {    public ListNode addTwoNumbers(ListNode l1, ListNode l2) {        int carry = 0;        ListNode head = l1!=null?l1:l2;        ListNode tail = head;        while (l1 != null && l2 != null) {            int sum = l1.val + l2.val + carry;            l1.val = sum%10;            carry = sum/10;            tail = l1;            l1 = l1.next;            l2 = l2.next;        }        if (l1 != null) {            tail.next = l1;            while (l1 != null) {                int sum = l1.val + carry;                l1.val = sum%10;                carry = sum/10;                tail = l1;                l1 = l1.next;            }            if (carry > 0){                tail.next = new ListNode(carry);            }        } else {            tail.next = l2;            while (l2 != null) {                int sum = l2.val + carry;                l2.val = sum%10;                carry = sum/10;                tail = l2;                l2 = l2.next;            }            if (carry > 0){                tail.next = new ListNode(carry);            }        }        return head;    }}