Add_two

 

Description

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 -> 8
Explanation: 342 + 465 = 807.

分析

大数相加 用链表存储.

code

#include<iostream>
class Solution
{
  public:
    ListNode *addTwoNumbers(ListNode *l1, ListNode *l2)
    {
        ListNode preHead(0), *p = &preHead;
        int extra = 0;
        while (l1 || l2 || extra)
        {
            int sum = extra + (l1 ? l1->val : 0) + (l2 ? l2->val : 0);
            p->next = new ListNode(sum % 10);
            p = p->next;
            extra = sum / 10;
            l1 = l1 ? l1->next : l1;
            l2 = l2 ? l2->next : l2;
        }
        return preHead.next;
    }
};