Add Two Numebers 两数相加
Link: https://leetcode.com/problems/add-two-numbers/
Problem:
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.
给定两个非空链表来表示两个非负整数。位数按照逆序方式存储，它们的每个节点只存储单个数字。将两数相加返回一个新的链表。
你可以假设除了数字 0 之外，这两个数字都不会以零开头。
Example:
Input: (2 -> 4 -> 3) + (5 -> 6 -> 4)
Output: 7 -> 0 -> 8
Explanation: 342 + 465 = 807.
Approach:
暴力，注意进位，dump节点的技巧。
Solution:
/**
* 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* cur_1=l1;
ListNode* cur_2=l2;
int flag=0; /*进位标志*/
ListNode* pre;
ListNode* dump=new ListNode(0); /*哑节点*/
ListNode* cur=dump;
while(cur_1!=NULL || cur_2!=NULL || flag!=0)
{
int sum=0;
if(cur_1!=NULL)
{
sum=sum+cur_1->val;
cur_1=cur_1->next;
}
if(cur_2!=NULL)
{
sum=sum+cur_2->val;
cur_2=cur_2->next;
}
sum=sum+flag;
flag=sum/10;
cur->next=new ListNode(sum%10); /*直接插入*/
cur=cur->next;
}
return dump->next;
}
};
