题解 | #【模板】链表#

import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int n = Integer.parseInt(sc.nextLine());
        MyLinked linked = new MyLinked();
        for(int i=0;i<n;i++){
            String[] tempData = sc.nextLine().split(" ");
            switch(tempData[0]){
                case "insert":
                    linked.insert(Integer.parseInt(tempData[1]),Integer.parseInt(tempData[2]));
                    break;
                case "delete":
                    linked.delete(Integer.parseInt(tempData[1]));
                    break;
            }
        }
        linked.output();
        sc.close();
    }
}

class MyLinked{
    private Node head;//头节点
    
    private int length;//链表的长度
    
    //创建一个单链表
    public MyLinked(){
        this.length = 0;
        head = new Node(null);
    }
    
    //向链表中添加数据
    public void insert(int value,int data){
        Node p = this.head;//前指针
        Node q = this.head.getNext();//后指针
        while(q!=null && q.getData()!=value){//加上q!=null,防止找到最后节点不结束而出现空指针错误(放前面)
            p = q;
            q = q.getNext();
        }
        if(q==null){//链表中没有所查找的数据,新数据插入末尾
            p.setNext(new Node(data,null));
            this.length++;
        }
        else{//找到目标数据
            p.setNext(new Node(data,q));
            this.length++;
        }
    }
    
    //删除链表中的数据
    public void delete(int data){
        if(isEmpty()){
            return;
        }
        Node p = this.head;
        Node q = this.head.getNext();
        while(q!=null && q.getData()!=data){
            p = q;
            q = q.getNext();
        }
        if(q==null){//所要删除的数据不存在
            return;
        }
        else{//找到，删除
            p.setNext(q.getNext());
            this.length--;
        }
    }
    
    //判空
    public boolean isEmpty(){
        if(this.length==0){
            return true;
        }
        return false;
    }
    
    //链表中的数据输出
    public void output(){
        if(isEmpty()){
            System.out.println("NULL");
            return;
        }
        Node temp = this.head.getNext();
        for(int i=0;i<this.length;i++) {
        	if (i==this.length-1) {
				System.out.print(temp.getData());
				break;
			}
        	else {
        		System.out.print(temp.getData()+" ");
                temp = temp.getNext();
        	}
        }
    }
}

class Node{
    private int data;//数据域
    
    private Node next;//指针域
    
    //创建一个头节点
    public Node(Node next){
        this.next = next;
    }
    
    //创建一个实际节点
    public Node(int data,Node next){
        this.data = data;
        this.next = next;
    }
    
    public int getData(){
        return this.data;
    }
    
    public void setData(int data){
        this.data = data;
    }
    
    public Node getNext(){
        return this.next;
    }
    
    public void setNext(Node next){
        this.next = next;
    }
}