Question

我有一个自定义的DLinkedList类，这个二进制搜索树类，我希望它按顺序使用递归返回双向链表，但我不知道从哪里开始

DLinkedList x = new DLinkedList();

public DLinkedList returnInOrderTraversal(){
    return IOT(rootNode); 
}

public DLinkedList IOT(BSTNode root){
    if(root == null) return x;
    IOT(root.leftChild)
    IOT(root.rightChild)
    x.add(//somehow add the root when the loop is finished)

    return x;

}

双重链接列表类：

public class DLinkedList {

    private class Node {
        private int value;
        private Node nextNode;
        private Node prevNode;

        public Node(int v) {
            value = v;
            nextNode = null;
            prevNode = null;
        }

        public int getValue() {
            return value;
        }

        public void setValue(int v) {
            value = v;
        }

        public Node getNextNode() {
            return nextNode;
        }

        public void setNextNode(Node n) {
            nextNode = n;
        }

        public Node getPrevNode() {
            return prevNode;
        }

        public void setPrevNode(Node n) {
            prevNode = n;
        }

    }

    // Holds a reference to the head and tail of the list
    private Node headNode;
    private Node tailNode;

    public DLinkedList() {
        headNode = null;
        tailNode = null;
    }

    public Object getHeadValue(){
        if (headNode == null)
            return null;
        return headNode.value;
    }

    public Object getTailValue(){
        if (tailNode == null)
            return null;
        return tailNode.value;
    }

    public void addAtHead(int o) {
        Node newNode = new Node(o); 
        newNode.setNextNode(headNode); 
        if (headNode != null)
            headNode.setPrevNode(newNode);
        headNode = newNode; 
        // special case for empty list
        if (tailNode == null)
            tailNode = newNode;
    }

    public void addAtTail(int o) {
        Node newNode = new Node(o);
        // this means that headNode == null too!
        if(tailNode == null){
            tailNode = newNode;
            headNode = newNode;
        }else{
            newNode.setPrevNode(tailNode);
            tailNode.setNextNode(newNode);
            tailNode = newNode;
        }
    }

    public Object deleteAtHead() {
        // list is empty 
        if(headNode == null){
            headNode = null;
            tailNode = null;
            return null;
        }
        // singleton: must update tailnode too
        if(headNode == tailNode){
            Object res = headNode.getValue();
            headNode = null;
            tailNode = null;
            return res;
        }

        Object res = headNode.getValue();
        headNode = headNode.getNextNode();
        headNode.setPrevNode(null);
        return res;
    }

    public Object deleteAtTail() {
        // list is empty 
        if(tailNode == null){
            headNode = null;
            tailNode = null;
            return null;
        }
        // singleton: must update tailnode too
        if(headNode == tailNode){
            Object res = tailNode.getValue();
            headNode = null;
            tailNode = null;
            return res;
        }
        Object res = tailNode.getValue();
        tailNode = tailNode.getPrevNode();
        tailNode.setNextNode(null);
        return res;
    }

}

Answer 1

为了按顺序获取元素，您希望在添加左侧之后但在添加右侧之前执行add（）。

add（）本身只需在列表末尾添加元素即可。

双向链接列表二进制搜索树按顺序遍历

1 个答案: