题解 | #【模板】链表#

import java.util.Scanner;

/**
 * @BelongsProject: homework
 * @Author: Ling xi_Li
 * @CreateTime: 2023-10-25 12-40
 * @Description: TODO
 */

class Node {
    private int data;
    private Node next;

    public Node() {
        this.data = 0;
        this.next = null;
    }

    public Node(int data) {
        this.data = data;
        this.next = null;
    }

    public Node getNext() {
        return next;
    }

    public int getData() {
        return data;
    }

    public void setNext(Node next) {
        this.next = next;
    }
}

class Link {

    //TODO head是带空节点的头指针
    private Node head;

    public Link() {
        head = null;
    }

    public Link(Node head) {
        this.head = head;
    }

    public boolean isEmptyLink() {
        return head.getNext() == null;
    }

    public void append(Node node) {
        if (isEmptyLink()) {
            this.head.setNext(node);
        } else {
            Node temp = this.head.getNext();
            while (temp.getNext() != null) {
                temp = temp.getNext();
            }
            temp.setNext(node);
        }
    }

    public void add(Node node) {
        if (isEmptyLink()) {
            this.head.setNext(node);
        } else {
            node.setNext(this.head.getNext());
            this.head.setNext(node);
        }
    }

    public void insert(int x, int y) {
        Node node = new Node(y);

        int flag = 0;
        Node temp = this.head;
        while (temp.getNext() != null) {
            if (temp.getNext().getData() == x) {
                node.setNext(temp.getNext());
                temp.setNext(node);
                flag = 1;
                break;
            }
            temp = temp.getNext();
        }
        if (flag == 0) {
            temp.setNext(node);
        }
    }

    public void remove(int num) {

        if (isEmptyLink()) return;

        Node temp = this.head;

        Node current = temp.getNext();

        while (current != null) {
            if (current.getData() == num) {
                temp.setNext(current.getNext());
                current.setNext(null);
                break;
            }
            temp = current;
            current = current.getNext();
        }
    }

    public void show() {

        if (isEmptyLink()) {
            System.out.println("NULL");
            return;
        }
        Node temp = this.head.getNext();
        while (temp != null) {
            System.out.print(temp.getData() + " ");
            temp = temp.getNext();
        }
    }
}

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别

        Link list = new Link(new Node());
        int n = in.nextInt();
        for (int i = 0; i < n; i++) {
            String op = in.next();
            if (op.equals("insert")) {
                list.insert(in.nextInt(), in.nextInt());
            } else if (op.equals("delete")) {
                list.remove(in.nextInt());
            }
        }
        list.show();
    }
}