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 -> 8Explanation: 342 + 465 = 807.

 

AC code:

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:        ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {        ListNode *head = NULL, *prev = NULL;        int carry = 0;        while (l1 || l2) {            int v1 = l1? l1->val: 0;            int v2 = l2? l2->val: 0;            int tmp = v1 + v2 + carry;            carry = tmp / 10;            int val = tmp % 10;            ListNode* cur = new ListNode(val);            if (!head) head = cur;            if (prev) prev->next = cur;            prev = cur;            l1 = l1? l1->next: NULL;            l2 = l2? l2->next: NULL;        }        if (carry > 0) {            ListNode* l = new ListNode(carry);            prev->next = l;        }        return head;    }};