Add Two Numbers

Question ：

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

code：

class Solution {  public:     ListNode *addTwoNumbers(ListNode *l1, ListNode *l2){    ListNode* phead =new ListNode(0);    ListNode* pTail =phead;    //int *temp ;    int carry = 0;    if(!l1)        return l2;    if(!l2)        return l1;    while(l1&&l2)    {        int val= l1->val+l2->val+carry;        carry = val/10;        pTail->next = new ListNode(val%10);        pTail = pTail->next;        l1 = l1->next;        l2 = l2->next;    }    ListNode* left = l1?l1:l2;    while(left)    {        int val= left->val+carry;        carry = val/10;        pTail->next= new ListNode(val%10);        pTail = pTail->next;        left = left->next;    }    if(carry)    {        pTail->next= new ListNode(carry);        pTail->next->next = NULL;    }    return phead->next;}};