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.

/** * Definition for singly-linked list. * struct ListNode { *     int val; *     struct ListNode *next; * }; */struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {    struct ListNode* l = (struct ListNode*)malloc(sizeof(struct ListNode));    int last_sum = l1->val + l2->val,this_sum;    l->val = last_sum % 10;    struct listNode* head = l;    l1 = l1->next;    l2 = l2->next;    while(l1 && l2){        struct ListNode* node = (struct ListNode*)malloc(sizeof(struct ListNode));        this_sum = l1->val + l2->val;        node->val = (last_sum/10 + this_sum)%10;        last_sum = last_sum/10 + this_sum;        l->next = node;        l = node;        l1 = l1->next;        l2 = l2->next;    }    struct ListNode* l12 = (struct ListNode*)malloc(sizeof(struct ListNode));    l12 = NULL;    if(l1) l12 = l1;    if(l2) l12 = l2;    if(l12){        if(last_sum < 10){            l->next = l12;            return head;        }        else{            while(l12){                struct ListNode* node = (struct ListNode*)malloc(sizeof(struct ListNode));                node->val = (last_sum/10 + l12->val)%10;                last_sum = last_sum/10 + l12->val;                l->next = node;                l = node;                l12 = l12->next;            }        }    }    if(last_sum/10){        struct ListNode* node = (struct ListNode*)malloc(sizeof(struct ListNode));        node->val = last_sum/10;        l->next = node;        l = node;    }    l->next = NULL;    return head;}