2. Add Two Numbers

Question

Total Accepted: 123735 Total Submissions: 554195 Difficulty: Medium

 

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

 

 to see which companies asked this question

Hide Tags

 

 

Show Similar Problems

 

new 新的节点参考了：

 

核心代码：

1 ListNode *p = new ListNode(sum % 10);2

 

比较好的思路：

直接用了 取余 和 /10 操作，少一步判断 是否要进位。

 

1 /** 2  * Definition for singly-linked list. 3  * struct ListNode { 4  *     int val; 5  *     ListNode *next; 6  *     ListNode(int x) : val(x), next(NULL) {} 7  * }; 8  */ 9 class Solution {10 public:11     ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {12         ListNode* tail = NULL;13         ListNode* head = NULL;14         int sum = 0;15         while(l1 != NULL || l2 != NULL){16             if(l1 != NULL){17                 sum += l1->val;18                 l1 = l1->next;19             }20             if(l2 != NULL){21                 sum += l2->val;22                 l2 = l2->next;23             }24             ListNode *p = new ListNode(sum % 10);25             if (head == NULL) {  26                 head = p;  27                 tail = p;  28             } else {  29                 tail->next = p;  30                 tail = p;  31             }  32             sum /= 10;33         }34         if(sum != 0){35             ListNode *p = new ListNode(sum % 10);36             tail->next = p;  37             tail = p;  38         }39         tail->next = NULL;40         return head;41     }42 };