LeetCode OJ:Add Two Numbers

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

/**
 * 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 *p=l1,*q=l2,*r;
        ListNode *nh=new ListNode(0);
        r=nh;
        int c=0,s;
        while(p||q){
            s=c;
            if(p)s+=p->val;
            if(q)s+=q->val;
            r->next=new ListNode(s%10);
            c=s/10;
            r=r->next;
            if(p)p=p->next;
            if(q)q=q->next;
        }
        if(c)r->next=new ListNode(c);
        return nh->next;
    }
};