【LeetCode】2. Add Two Numbers 解题小结

题目：　　

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

考查链表的用法

/**
 * 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 Res(0), *p = &Res;
        
        int flag = 0;
        while (l1 != NULL || l2 != NULL || flag){
            int bitSum = (l1?l1->val:0) +(l2?l2->val:0)+flag;
            flag = bitSum/10;
            p->next = new ListNode(bitSum%10);
            p = p->next;
            l1 = l1?l1->next:l1;
            l2 = l2?l2->next:l2;
        }
    
       return Res.next;
    }
};