2. Add Two Numbers
难度:Medium
刷题内容
原题连接
- https://leetcode.com/problems/add-two-numbers
内容描述
给定两个链表代表两个非负数，求这两个数的和
(2 -> 4 -> 3) + (5 -> 6 -> 4)
因为 342 + 465 = 807
所以返回 7 -> 0 -> 8
解题方案
思路
这题的的关键在于链表的数储存是倒序的，因此只要从链表头相加，再将所得数挨个储存即可，但是要注意两数相加有可能大于10要进一位。
/**
* 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* current;
ListNode* ret = nullptr;
int num = 0;
while(l1 && l2)
{
int sum = l1 ->val + l2 ->val + num;
ListNode* node = new ListNode(sum % 10);
num = sum / 10;
ret ? current ->next = node : ret = node;
current = node;
l1 = l1 ->next;
l2 = l2 ->next;
}
if(l2)
l1 = l2;
while(l1)
{
int sum = num + l1 ->val;
ListNode* node = new ListNode(sum % 10);
num = sum / 10;
current ->next = node;
current = node;
l1 = l1 ->next;
}
if(num)
{
ListNode* node = new ListNode(num);
current ->next = node;
}
return ret;
}
};
