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;    }};