判断是否是二叉树的子树

/**
 * BST树的节点类型
 * @param <T>
 */
class BSTNode <T extends Comparable<T>>{
    private T data; // 数据域
    private BSTNode<T> left; // 左孩子域
    private BSTNode<T> right; // 右孩子域

    public BSTNode(T data, BSTNode<T> left, BSTNode<T> right) {
        this.data = data;
        this.left = left;
        this.right = right;
    }

    public T getData() {
        return data;
    }

    public void setData(T data) {
        this.data = data;
    }

    public BSTNode<T> getLeft() {
        return left;
    }

    public void setLeft(BSTNode<T> left) {
        this.left = left;
    }

    public BSTNode<T> getRight() {
        return right;
    }

    public void setRight(BSTNode<T> right) {
        this.right = right;
    }
}

/**
 * BST树的实现
 * @param <T>
 */
class BST<T extends Comparable<T>>{
    private BSTNode<T> root; // 指向根节点

    /**
     * BST树的初始化
     */
    public BST() {
        this.root = null;
    }
     /**
     * 判断是否是二叉树的子树
     * @param tree
     * @return
     */
    public boolean isChildTree(BST<T> tree){
        BSTNode<T> cur = this.root;
        while (cur!=null){
            if (cur.getData().compareTo(tree.root.getData())>0){
                cur = cur.getLeft();
            }if (cur.getData().compareTo(tree.root.getData())<0){
                cur = cur.getRight();
            }else {
                break;
            }
        }
        if (cur==null){
            return false;
        }
        return isChildTree(cur,tree.root);
    }

    private boolean isChildTree(BSTNode<T> f, BSTNode<T> c) {
        if(f == null && c == null){
            return true;
        }

        if(f == null){
            return false;
        }

        if(c == null){
            return true;
        }

        if(f.getData().compareTo(c.getData()) != 0){
            return false;
        }

        return isChildTree(f.getLeft(), c.getLeft())
                && isChildTree(f.getRight(), c.getRight());
    }
}