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;

    }

};