二分探索木

BST.java

// How to Implement Binary Search Tree in Java? Example
// https://javarevisited.blogspot.com/2015/10/how-to-implement-binary-search-tree-in-java-example.html#axzz4wnEtnNB3

import java.util.Stack;

public class BST {

    private class Node {
        private int data;
        private Node left, right;

        public Node(int value){
            data = value;
            left = right = null;
        }
    }

    private Node root;

    public BST() {
        root = null;
    }

    public Node getRoot() {
        return root;
    }

    public boolean isEmpty() {
        return null == root;
    }

    public int size() {
        Node current = root;
        int size = 0;
        Stack<Node> stack = new Stack<Node>();

        while (!stack.isEmpty() || current != null){
            if (current != null){
                stack.push(current);
                current = current.left;
            } else {
                size++;
                current = stack.pop();
                current = current.right;
            }
        }
        return size;
    }

    public void clear() {
        root = null;
    }

}