package com.lianbiao.java;
//19. 删除链表的倒数第 N 个结点
public class five {

	public ListNode removeNthFromEnd(ListNode head, int n) {
		ListNode dummy = new ListNode(-1);
		dummy.next = head;
		
		ListNode slow = dummy;
		ListNode fast = dummy;
		
		while(n >= 0) {//=号 使得fast移动了n+1步，最后保证slow指向了待删除结点的上一个结点
			fast = fast.next;
			n--;
		}

		while(fast != null) {
			slow = slow.next;
			fast = fast.next;
		}
		slow.next = slow.next.next;
		
		return dummy.next;
    }
}


class ListNode {
	 
	 int val;
	 ListNode next;
	public ListNode(int val) {
		super();
		this.val = val;
	}
	@Override
	public String toString() {
		return "ListNode [val=" + val + ", next=" + next + "]";
	}
	
	 
}