题解 | #从单向链表中删除指定值的节点#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        int n = in.nextInt();
        int first = in.nextInt();//头结点
        int[][] array = new int[n - 1][2];

        for (int i = 0; i < n - 1; i++) {
            array[i][0] = in.nextInt();
            array[i][1] = in.nextInt();
        }

        int deleteKey = in.nextInt();
        in.close();



        LinkList list = new LinkList(n);
        list.insertFirst(first);
        for (int i = 0; i < array.length; i++) {
            if(list.isContainTheKey(array[i][0])){
               list.insertAfter(array[i][0],array[i][1]);
//               list.display();
            }else{
               list.insertBefore(array[i][1],array[i][0]);
//               list.display();
            }

        }
       
        list.deleteByKey(deleteKey);
        list.display();



    }

    static class Link {

        public int  data;

        public Link next;

        Link(int data) {

            this.data = data;
        }

        public int peek() {

            return data;
        }

    }

    static class LinkList {

        private Link first;

        private int size;

        String [] result = new String[size];

        public LinkList(int n) {
            first = null;
            size = n;
        }


        public boolean isEmpty() {

            return (first == null);
        }

        public void insertFirst(int data) {

            Link newLink = new Link(data);
            newLink.next = first;//下一个为空
            first = newLink;

        }

        public Link deletFirst() {
            Link temp = first;
            first = first.next;

            return temp;
        }


        public void display() {
            // System.out.println();
            String str = "";
            Link current = first;
            while (current != null) {
//           current.display();
                str += current.data + " ";
                current = current.next;
            }
            result = str.split(" ");
            for (int i = result.length - 1; i >= 0; i--) {
                System.out.print(result[i]+" ");
            }
        }


        public  boolean isContainTheKey(int k) {
            Link current = first;
            while (current.next != null) {
                current = current.next;
                if (current.data == k)
                    return true;
            }
            return false;

        }

        public void insertLast(int data) {
            Link last = new Link(data);
            Link current = first;
            while (current.next != null) {
                current = current.next;
            }
            current.next = last;
        }

        public void deleteByKey(int key) {
            Link previous = first;
            Link current = first;
            while (current.data != key) {
                previous = current;
                current = current.next;
            }
            if (first == current) {
                first = first.next;
            } else {
                previous.next = current.next;
            }
            size--;

        }


        public void insertBefore(int key, int data) {

            if (key == first.data) {
                insertFirst(data);
//           this.display();
            } else {
                Link previous = first;
                Link current = first;
                Link  insert  = new Link(data);
                while (current.data != key && current.next != null) {
                    previous = current;
                    current = current.next;
                }
                previous.next = insert;
                insert.next = current;
            }

        }


        public  void insertAfter(int key, int data) {
            Link current = first;
            Link after = first;
            Link insert = new Link(data);
            while (current.next != null && current.data != key) {
                current = current.next;
                current.next = after;
            }
            if (current.next == null) {
                current.next = insert;
            } else {
                current.next = insert;
                insert.next = after;
            }

        }



    }

}