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;    }};