【Leetcode】2、Add Two Numbers

题目

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.

ex：

Input:(2->4->3)+(5->6->4)

Output:7->0->8

Explanation:7->0->8

思路

就是用链表模拟加法，没什么特别的思路

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