【一天一道LeetCode】#19. Remove Nth Node From End of List

一天一道LeetCode系列

（一）题目

（二）解题

/**
* Definition for singly-linked list.
* struct ListNode {
*     int val;
*     ListNode *next;
*     ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode* removeNthFromEnd(ListNode* head, int n) {
if(n == 0) return head;
ListNode* ptemp = head;
for(int i = 0 ; i < n ;i++)
{
ptemp = ptemp->next;
}
ListNode* pNth = head;
ListNode* pre = head;
while(ptemp!= NULL)
{
pre = pNth;
ptemp = ptemp->next;
pNth = pNth->next;
}
if(pNth == head)//如果是头节点
{
head = head->next;
}
else pre->next = pNth->next;//非头节点
free(pNth);
return head;
}
};