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;
    }
};