Question

我是编码新手，我正在学习Java中的链接列表。下面的代码显示了两个类。一个类反转名为ReverseASinglyLinkedList类的单链表，另一个类是LinkedListNode类。我编写代码来测试我的代码是否真正有用，我遇到了问题。在主要内容中，我想传递以下LinkedList：[7, 14, 21, 28]。我希望代码返回[28, 21, 14, 7]。首先，我如何将[7, 14, 21, 28]传递给主？我试图编写代码，但它有错误。我觉得我错过了一些简单的东西，但我几乎就在那里。感谢。

public static void main(String[] args) {
    LinkedListNode list = new LinkedListNode();
    list.head = new LinkedListNode(7);
    list.head.next = new LinkedListNode(14);
    list.head.next.next = new LinkedListNode(21);
    list.head.next.next.next = new LinkedListNode(28);
    System.out.println(list.data);
    System.out.println("Given Linked list");
    list.printList(list.head);
    list.head = reverse_iterative(list.head);
    System.out.println("");
    System.out.println("Reversed linked list ");
    list.printList(list.head);
}

public class LinkedListNode {
    public LinkedListNode next, prev, last;
    public int data;

    public LinkedListNode(int d, LinkedListNode n, LinkedListNode p) {
        data = d;
        setNext(n);
        setPrevious(p);
    }

    public LinkedListNode(int d) {
        data = d;
    }

    public LinkedListNode() {
    }

    public void setNext(LinkedListNode n) {
        next = n;
        if (this == last) {
            last = n;
        }
        if (n != null && n.prev != this) {
            n.setNext(this);
        }
    }

    public void setPrevious(LinkedListNode p) {
        prev = p;
        if (p != null && p.next != this) {
            p.setNext(this);
        }
    }

    public LinkedListNode clone() {
        LinkedListNode next2 = null;
        if (next != null) {
            next2 = next.clone();
        }
        LinkedListNode head2 = new LinkedListNode(data, next2, null);
        return head2;
    }
}

public class ReverseASinglyLinkedList {
    public static LinkedListNode reverse_iterative(
            LinkedListNode head) {
        // no need to reverse if head is null
        // or there is only 1 node.
        if (head == null ||
                head.next == null) {
            return head;
        }

        LinkedListNode list_to_do = head.next;
        LinkedListNode reversed_list = head;

        reversed_list.next = null;

        while (list_to_do != null) {
            LinkedListNode temp = list_to_do;
            list_to_do = list_to_do.next;

            temp.next = reversed_list;
            reversed_list = temp;
        }

        return reversed_list;
    }
}

Answer 1

只是一个建议您可以创建一个包含数据成员Data，previous和next Node的Node类（通常称为前一个节点和下一个节点的“指针”）。然后创建一个名为List的类，其中您将数据成员作为Node实例，并具有Insert和reverse等功能，您可以在列表中执行操作。
这是你如何实现它：

 class LList{
    private class Node{
        private int data;
        private Node previous;
        private Node next;
        Node(int data){
            this.data = data;
            this.next = this.previous = null;
        }
    }
    private Node head;
    LList(){
        this.head = null;
    }
    public void insertAtFront(int data){
        Node temp = new Node(data);
        temp.next = head;
        temp.previous = null;
        if(this.head!= null)this.head.previous = temp;
        this.head = temp;
    }
    void reverse() {
        Node temp = null;
        Node current = this.head;

        while (current != null) {
            temp = current.previous;
            current.previous = current.next;
            current.next = temp;
            current = current.previous;
        }

        if (temp != null) {
            this.head = temp.previous;
        }
    }
    public  void printList(Node temp){
        while(temp!=null){
            System.out.println(temp.data);
            temp = temp.next;
        }
        System.out.println();
    }
    public Node returnNode(){
        return this.head;
    }
}

public static void main(String[] args) {
    LList var1 = new LList();
    int[] a = {10,20,30,40};
    for(int k : a)var1.insertAtFront(k); //List will look like 40->30->20->10 
    var1.printList(var1.returnNode());
    var1.reverse();
    var1.printList(var1.returnNode());
}

此外，由于您有下一个和之前的“指针”，您的实现看起来像一个双向链表。

这是我写的原始代码：

public class LinkedListSO_1_7_2018 {
    static class LList{
        private static class Node{
            // same thing as that of the above
            Node(int data){
               //just like before
            }
        }
        private Node head;
        LList(){
            //same thing 
        }
        public void insertAtFront(int data){
           //same thing
        }
        void reverse() {
            //same thing
        }
        public  void printList(Node temp){
            //and again
        }
        public Node returnNode(){
            //and again
        }
    }

    public static void main(String[] args) {
        LList var1 = new LList();
        int[] a = {10,20,30,40};
        for(int k : a)var1.insertAtFront(k);
        var1.printList(var1.returnNode());
        var1.reverse();
        var1.printList(var1.returnNode());

    }
}

如何实例化我的Java代码中显示的LinkedListNode？

1 个答案: