LeetCode---(2) Add Two Number

Problem

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

最终的进位需要注意

/**
* 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) {
if(l1==NULL&&l2==NULL)
return NULL;

ListNode *p=l1,*q=l2;
ListNode* result=new ListNode(0);
ListNode* current=result;

int value=0;
int carry=0;
while(p!=NULL&&q!=NULL)
{
value=p->val+q->val+carry;
current->next=new ListNode(value%10);
current=current->next;
carry=value/10;
p=p->next;
q=q->next;
}
while(p!=NULL)
{
value=p->val+carry;
current->next=new ListNode(value%10);
current=current->next;
carry=value/10;
p=p->next;
}
while(q!=NULL)
{
value=q->val+carry;
current->next=new ListNode(value%10);
current=current->next;
carry=value/10;
q=q->next;
}
if(carry!=0)
current->next=new ListNode(1);

current=result;
result=result->next;
delete current;
return result;
}
};