如何找到并获取用户输入单链表的中间元素？

Question

我正在制作一个程序，让用户添加整数元素，获取其长度，并获取其中间元素。我的问题是，我不知道写什么来获得中间元素。我试图在互联网上搜索如何下载，但我找不到适合这个程序的代码行。

如何找到并获取用户输入单链表的中间元素？

 import java.util.Scanner;

 class Node
{
 int data;
 Node link; 
 Node next;
 public Node()
{
    link = null;
    data = 0;        
    next = null; 
   
}    
 public Node(int d,Node n)
{
    data = d;
    link = n;
}    
 public void setLink(Node n)
{
    link = n;
}    
 public void setData(int d)
{
    data = d;
}    
 public Node getLink()
{
    return link;
}    
 public int getData()
{
    return data;
}
}

 class LinkedList
{
  Node start;
  Node end;
  public int length;


 public LinkedList()
{
    start = null;
    end = null;
    length = 0;
}    
public int getLength()
{
    return length;
}    

 public void insert(int val)
{
     Node nptr = new Node(val,null);    
    length++ ;    
    if(start == null) 
    {
        start = nptr;
        end = start;
    }
    else 
    {
        end.setLink(nptr);
        end = nptr;
    }
}
 public void display()
{
    System.out.print("\nSingly Linked List = ");
       
    if (start.getLink() == null) 
    {
        System.out.println(start.getData() );
        return;
    }
    Node ptr = start;
    System.out.print(start.getData()+ " -> ");
    ptr = start.getLink();   
    while (ptr.getLink() != null)
    {
        System.out.print(ptr.getData()+ " -> ");
        ptr = ptr.getLink();
    }
    System.out.print(ptr.getData()+ " -> null\n");
 }
 }
  public class SinglyLinkedList
{    
  public static void main(String[] args)
 {             
    Scanner scan = new Scanner(System.in);
    LinkedList list = new LinkedList();         
    char ch;
    do
    {
        System.out.println("\nSingly Linked List\n");                     
        System.out.println("Enter integer element to insert:");
        list.insert( scan.nextInt() );       
        System.out.println("Length of the Linked List: "+ list.getLength() ); 
        System.out.println("Middle Element of the Linked List: ");  
        list.display();            
        System.out.println("\nDo you want to continue (Type y or n) \n");
        ch = scan.next().charAt(0);                        
    } while (ch == 'Y'|| ch == 'y');               
}
}

Answer 1

由于您已经在类中维护了length属性，因此我们可以使用该属性查找链接列表的中间部分。如果列表中有偶数个元素，则返回ceil（mid），即1-

public Node getMid() {
    if (length == 0) return null;
    int mid = length / 2;
    Node ptr = start;
    while (mid-- > 0) {
        ptr = ptr.getLink();
    }
    return ptr;
}