19.txt

/**
 * 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 == nullptr || n == 0) return head;
        ListNode prehead(0);
        prehead.next = head;   //prehead.   ²»ÊÇ->
        ListNode* fast = &prehead, *slow = &prehead;

        for(int i = 1; i <= n+1;i++)  fast = fast ->next;   //i ´Ó1 ¿ªÊ¼

        while(fast != nullptr )
        {
            slow = slow -> next;
            fast = fast->next;

        }
        ListNode* temp = slow ->next;
        slow ->next = slow ->next-> next;
        delete temp;



        return prehead.next;



        
    }
};