java - 双链表实现回文检查器

Question

嗨，我正在尝试实现此代码来检查回文并删除并添加到左侧和右侧。我无法弄清楚如何从列表中删除并添加请帮忙。

public class DLL {

        private charNode DLLleft, DLLright;

         class charNode {
                 char data;
                 charNode left;
                 charNode right;

                public charNode(char D, charNode l, charNode r) {
                    data=D;
                    left = l;
                    right = r;
                }
         }  

        public DLL() {
            DLLleft= null;
            DLLright= null;
        }
        public void addDLLleft(char data){
            charNode temp = new charNode(data, null, DLLleft);
            if(DLLleft ==null)
                DLLright = temp;
            else
                DLLleft.left=temp;
                DLLleft = temp;
        }
        public void addDLLright(char data){
            charNode temp = new charNode(data, null, DLLright);
            if(DLLright == null)
                DLLleft = temp;
            else
                DLLright.right = temp;
                DLLright = temp;
        }
        public char removeDLLright(char data){
            charNode temp = DLLright;
            while (data == DLLright.data);

        }
        public void printRtoL(){
            charNode temp = DLLright;
            while(temp != null){
                System.out.println(temp.data);
                temp = temp.left;
            }
        }
        public void printLtoR(){
            charNode temp = DLLleft;
            while(temp != null){
                System.out.println(temp.data);
                temp = temp.right;
            }
        }
        public void clearDLL(){
            DLLleft = null;
            DLLright = null;
        }
    }

这是我到目前为止所拥有的，但我坚持如何从列表中删除并从回文中检查。

Answer 1

使用一种递归方法这将非常简单......但是，让我们玩点乐趣。为了使其更具可读性，我将重命名您的一些变量(我将保留您的方法名称，以便您知道发生了什么)。

public class DLL<E> {

    private charNode head;
    private charNode tail;
    private int size;

    private class charNode {
             E element;
             charNode next;
             charNode prev;

            public charNode(E element, charNode next, charNode prev) {
                this.element = element;
                this.next = next;
                this.prev = prev;
            }
     }  

    public void addDLLleft(E element){
        charNode temp = new charNode(element, head, null);
        if(head != null ) {
          head.prev = temp;
        }
        head = temp;
        if(tail == null) {
          tail = temp;
        }
        size++;
    }
    public void addDLLright(char data){
        charNode temp = new charNode(element, null, tail);
        if(tail != null) {
          tail.next = temp;
        }
        tail = temp;
        if(head == null) {
          head = temp;
        }
        size++;
    }

    public E removeDLLleft(){
       if (size == 0) throw new NoSuchElementException();
       charNode temp = head;
       head = head.next;
       head.prev = null;
       size--;
       return temp.element;
    }

    public E removeDLLright(){
       if (size == 0) throw new NoSuchElementException();
       Node temp = tail;
       tail = tail.prev;
       tail.next = null;
       size--;
       return temp.element;

    }

    public void printRtoL(){
        charNode temp = tail;
        while(temp != null){
           System.out.println(temp.element);
           temp = temp.prev;
        }
    }

    public void printLtoR(){
       charNode temp = head;
       while(temp != null){
           System.out.println(temp.element);
           temp = temp.next;
       }
    }

    public void clearDLL(){
        DLLleft = null;
        DLLright = null;
    }

   // Necessary
   public int size() {
        return size;
   }
}