删除指定节点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) {
        ListNode *temp = head;
        int len=0,m;
        while(temp){
            ++len;
            temp=temp->next;
        }
        if(n==len)
            return head->next;
        m=len-n;
        ListNode *temp1=head;
        while(m>1){
            temp1=temp1->next;
            --m;
        }
        temp1->next=temp1->next->next;
        return head;
            
    }
};