leetcode[19]Remove Nth Node From End of List

Given a linked list, remove the nth node from the end of list and return its head.

For example,

Given linked list: 1->2->3->4->5, and n = 2.

After removing the second node from the end, the linked list becomes 1->2->3->5.

Note:
Given n will always be valid.
Try to do this in one pass.

/**
* 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(head==NULL||head->next==NULL)return NULL;
ListNode *former=head;
ListNode *later=head;
ListNode *temp=NULL;
int count=0;
while(former->next)
{
count++;
former=former->next;
if(count>=n)
{
temp=later;
later=later->next;
}
}
if(temp==NULL)head=later->next;
else temp->next=later->next;
delete later;
return head;
}
};