Leetcode 19. Remove Nth Node From End of List
https://leetcode.com/problems/remove-nth-node-from-end-of-list/
/**
* 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) {
using namespace std;
/*
边界:要删的可能是第一个,也可能是最后一个;
*/
ListNode *p=head,*pre=head;
while(n--) p=p->next;
if(p==NULL){
head=head->next;
delete pre;
return head;
}
p=p->next;
while(p){
p=p->next;
pre=pre->next;
}
p=pre->next;
pre->next=p->next;
delete p;
return head;
}
};