class Node<T>{//节点类
	public T data;
	public Node<T> next;
	public Node() {}
	public Node(T data) {
		this.data = data;
	}
}
public class MyList<T> {//链表类
	private Node<T> head = new Node<T>();
	public int nodeSize() {//链表大小
		int sum=0;
		Node<T> p = new Node<T>();
		p=head;
		while(p.next!=null) {
			sum++;
			p=p.next;
		}
		return sum;
	}
	public void addNode(T data) {//往链表尾部添加节点，具体位置添加的方法还没搞，和删除差不多
		Node<T> node = new Node<T>();
		if(head.next==null) {
			head.next=node;
			node.data=data;
			node.next=null;
		}else {
			Node<T> p = new Node<T>();
			p=head;
			while(p.next!=null) {
				p=p.next;
			}
			p.next=node;
			node.data=data;
			node.next=null;
		}
	}
	public void seeNode() {//打印链表
		Node<T> p = new Node<T>();
		p=head;
		while(p.next!=null) {
			System.out.println(p.next.data);
			p=p.next;
		}
	}
	public void changeNode(int n,T data) {//修改链表的值
		int m=0;
		Node<T> p = new Node<T>();
		p=head;
		while(p.next!=null) {
			p=p.next;
			if(n==m) {
				p.data = data;
				break;
			}
			m++;
		}
	}
	public void deleteNode(int n) {//删除下标为n的节点，下标从0开始
		int m=0;
		Node<T> p = new Node<T>();
		p=head;
		if(n==0) {
			Node<T> q = new Node<T>();
			q=p.next;
			head.next=q.next;
		}else{
			while(p.next!=null) {
				p=p.next;
				if(n-1==m) {
					break;
				}
				m++;
			}
			Node<T> q = new Node<T>();
			q=p.next;
			p.next=q.next;
		}
	}
	public static void main(String[] args) {
		MyList<Integer>myList= new MyList<Integer>();
		myList.addNode(10);
		myList.addNode(90);
		myList.addNode(80);
		myList.addNode(40);
		myList.changeNode(0, 20);
		myList.deleteNode(1);
		System.out.println(myList.nodeSize());
		myList.seeNode();
	}
}