JAVA之查找二叉树ADT

/*
 * 查找二叉树ADT：
 * 性质：对于树中每个节点X，它的左子树所有项的值小于X中的项
 * 	而它的右子树所有项的值大于X中的项
 */
public class BinarySearchTree<AnyType extends Comparable<? super AnyType>> {
	/*
	 * 树节点元素
	 */
	private static class BinaryNode<AnyType>{
		AnyType element;	//The data in the node(数据)
		BinaryNode<AnyType> left;	//lefi Child(左孩子：必须要比祖先节点小)
		BinaryNode<AnyType> right;	//right Child(右孩子：必须要比祖先节点大)
		public BinaryNode(AnyType theElement){
			this(theElement, null, null);
		}
		public BinaryNode(AnyType theElement, BinaryNode<AnyType> lt, BinaryNode<AnyType> rt){
			element = theElement;
			left = lt;
			right = rt;
		}
	}
	
	private BinaryNode<AnyType> root;	//根节点
	
	public boolean isEmpty(){
		return root == null;
	}
	
	public BinarySearchTree(){
		root = null;
	}
	
	public void makeEmpty(){
		root = null;
	}
	
	public boolean contains(AnyType x){
		return contains(x, root);
	}
	
	/*
	 * 利用递归的思想来递归调用
	 */
	private boolean contains(AnyType x, BinaryNode<AnyType> t){
		if(t == null)
			return false;
		int compareResult = x.compareTo(t.element);
		
		if(compareResult < 0)
			return contains(x, t.left);
		else if(compareResult > 0)
			return contains(x, t.right);
		else
			return true;
	}
	
	/*
	 * 取树中的最小值
	 */
	public AnyType findMin(){
		if(isEmpty())
			throw new NullPointerException();
		return findMin(root).element;
	}
	
	private BinaryNode<AnyType> findMin(BinaryNode<AnyType> t){
		if(t == null)
			return null;
		else if(t.left == null)
			return t;
		return(findMin(t.left));
	}
	/*
	 * 取树中的最大值
	 */
	public AnyType findMax(){
		if(isEmpty())
			throw new NullPointerException();
		return findMax(root).element;
	}
	
	private BinaryNode<AnyType> findMax(BinaryNode<AnyType> t){
		if(t == null)
			return null;
		else if(t.right == null)
			return t;
		return findMax(t.right);
	}
	
	/*
	 * 插入数据
	 */
	public void insert(AnyType x){
		root = insert(x, root);
	}
	
	private BinaryNode<AnyType> insert(AnyType x, BinaryNode<AnyType> t){
		if(t == null)
			return new BinaryNode<>(x, null, null);
		
		int compareResult = x.compareTo(t.element);
		
		if(compareResult < 0)
			t.left = insert(x, t.left);
		if(compareResult > 0)
			t.right = insert(x, t.right);
		else
			;
			return t;
	}
	
	/*
	 * 删除节点
	 */
	public void remove(AnyType x){
		root = remove(x, root);
	}
	private BinaryNode<AnyType> remove(AnyType x, BinaryNode<AnyType> t){
		if(t == null)
			return t;
		
		int compareResult = x.compareTo(t.element);
		
		if(compareResult < 0)
			t.left = remove(x, t.left);
		else if(compareResult > 0)
			t.right = remove(x, t.right);
		else if(t.left != null && t.right != null){
			t.element = findMin(t.right).element;
			t.right = remove(t.element, t.right);
		}else
			t = (t.left != null)? t.left : t.right;
		return t;
	}
	
	public void printTree(){
		if(isEmpty())
			System.out.println("空树");
		else
			printTree(root);
	}
	
	private void printTree(BinaryNode<AnyType> t){
		if(t != null){
			printTree(t.left);
			System.out.print(t.element+" ");
			printTree(t.right);
		}
	}
	

/*

 *		测试代码

*/
	public static void main(String[] args){
		BinarySearchTree<Integer> bst = new BinarySearchTree<>();
		bst.insert(6);
		bst.insert(2);
		bst.insert(8);
		bst.insert(1);
		bst.insert(4);
		bst.insert(3);
		bst.printTree();
		System.out.println("最小值：" + bst.findMin());
	}
}