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.

Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8

思路：
其实就是将整数相加，只不过这里各个位放在了链表中，要考虑到进位，且如果进位后，原先已无节点，要自己new一个节点。具体思路见注释。

代码：

/*** 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* newnode1 = l1;//初始化newnode1、newnode2分别指向l1、l2ListNode* newnode2 = l2;ListNode* pre1;//用来指向前一个节点ListNode* pre2;int flow = 0;//当前位的进位int res = 0;//用来计算当前位的和+flowwhile (newnode1&&newnode2){//如果当前位两个链表都有值 res = newnode1->val + newnode2->val+flow;//就将两个链表当前位的值和flow相加newnode1->val = res % 10;//res对10取余，即为相加后的值，赋给newnode1和newnode2当前位newnode2->val = newnode1->val;flow = res / 10;//计算当前位的flowpre1 = newnode1;//此时pre1、pre2指向newnode1和newnode2，保留这两个位置pre2 = newnode2;newnode1 = newnode1->next;//newnode1、newnode2分别指向它们的下一个newnode2 = newnode2->next;}if (newnode1 == NULL&&newnode2 != NULL){//如果newnode1为空而newnode2不为空while (newnode2 && (newnode2->val + flow) >= 10){//当newnode2不为空且newnode2的值+flow>=10时res = newnode2->val + flow;//计算resnewnode2->val = res % 10;//将res对10取余赋给newnode2当前位flow = res / 10;//计算当前位的flowpre2 = newnode2;//pre2继续保留newnode2newnode2 = newnode2->next;//newnode2指向下一个位置}//跳出while循环后，有两种情况if (newnode2==NULL&&flow != 0){//如果是newnode2==NULL,且此时flow不为0pre2->next = new ListNode(flow);//要将pre2指向一个新建的节点，且值为flow}else if ((newnode2->val + flow) < 10){//如果是newnode2->val+flow<10,也就是不会再进位newnode2->val += flow;//当前位直接加flow}return l2;//最终返回l2即可}else if (newnode1 != NULL&&newnode2 == NULL){//newnode1不为空且newnode2为空时，逻辑和前一个一样，只是返回l1while (newnode1 && (newnode1->val + flow) >= 10){res = newnode1->val + flow;newnode1->val = res % 10;flow = res / 10;pre1 = newnode1;newnode1 = newnode1->next;}if (newnode1==NULL&&flow != 0){pre1->next = new ListNode(flow);}else if ((newnode1->val + flow) < 10){newnode1->val += flow;}return l1;//返回l1}else if (newnode1 == NULL&&newnode2 == NULL){//如果两个都为空if (flow != 0){//但是进位不为0pre1->next = new ListNode(flow);//随便将pre1或者pre2的下一个指向一个new的节点，值为flow}return l1;//如果是用pre1，则返回l1；如果是用pre2，则返回l2}}
};

输出结果： 32ms

LeetCode 2. Add Two Numbers相关推荐

LeetCode之Add Two Numbers
LeetCode之Add Two Numbers 题目:You are given two linked lists representing two non-negative numbers. Th ...
LeetCode 445. Add Two Numbers II
LeetCode 445. Add Two Numbers II Solution1:我的答案利用了栈,这样就不用翻转链表了... /*** Definition for singly-linked ...
【注意】LeetCode 2. Add Two Numbers
LeetCode 2. Add Two Numbers 这种沙比提怎么都写不对了??? Solution1:学习这种写法 /*** Definition for singly-linked list. ...
LeetCode 445. Add Two Numbers II--面试算法题--C++,Python解法
题目地址:Add Two Numbers II - LeetCode You are given two non-empty linked lists representing two non-neg ...
[Leetcode] 445. Add Two Numbers II
问题: https://leetcode.com/problems/add-two-numbers-ii/#/description 思路:该题与"415. Add Strings" ...
LeetCode:2. Add Two Numbers
https://leetcode.com/problems/add-two-numbers/description/ 内容描述 You are given two non-empty linked l ...
leetcode 【 Add Two Numbers 】 python 实现
题目: You are given two linked lists representing two non-negative numbers. The digits are stored in r ...
leetcode 2. Add Two Numbers | 2. 两数相加（Java）
题目 https://leetcode.com/problems/sum-of-two-integers/ 题解需要注意当两个链表不一样长时的收尾处理. /*** Definition for ...
Leetcode: 2. Add Two Numbers
一直想用一个进位变量来存贮进位值,但老是考虑不周全,下面是我自己写的bug代码,考虑不周,因为l1或者l2都有可能为null class Solution {public ListNode addTw ...

LeetCode 2. Add Two Numbers

LeetCode 2. Add Two Numbers相关推荐

最新文章

热门文章