二叉树的建立、销毁算法

// 构造一棵二叉树
template < typename T >
class BinarySearchTree
{
private:
    struct MyNode
    {
        MyNode* left;
        MyNode* right;
        MyNode* parent;
        T value;
    };
    MyNode* root;
public:

    void Push( const T& node )
    {
        MyNode* pNode = this->root;
        MyNode* pNodeNow = NULL ;

        if  ( this->root == NULL  )
        {
            this->root = new MyNode();
            this->root->value = node;
            this->root->left = this->root->right = this->root->parent = NULL;
            return ;
        }
        else
        {
            while ( pNode )
            {
                if ( node == pNode->value )
                {
                    return;
                }
                // 叶子结点, 插入
                if ( !pNode->left && !pNode->right  )
                {
                    pNodeNow = new MyNode();
                    pNodeNow->value = node;
                    node < pNode->value ? pNode->left = pNodeNow :  pNode->right = pNodeNow;
                    return;
                }
                else if ( node < pNode->value )
                {
                    if (  pNode->left )
                    {
                        pNode = pNode->left;
                    }
                    else
                    {
                        pNodeNow = new MyNode();
                        pNodeNow->value  = node;
                        pNode->left = pNodeNow;
                        return;
                    }

                }
                else if ( node > pNode->value )
                {
                    if ( pNode->right )
                    {
                        pNode = pNode->right;
                    }    
                    else
                    {
                        pNodeNow = new MyNode();
                        pNodeNow->value  = node;
                        pNode->right = pNodeNow;
                        return;
                    }
                }    
            }

        }
    }
    BinarySearchTree()
    {
        this->root = NULL;
    }
    ~BinarySearchTree()
    {
        Destory( this->root );
    }
    void Destory( MyNode* pNode )
    {
        // 递归遍历并删除每个结点
    if  ( !pNode )
        {
            return;
        }
        Destory( pNode->left );
        pNode->left = NULL;
        Destory( pNode->right);
        pNode->right = NULL;
        cout << "delete node" << pNode->value  << endl;
        delete pNode ;
    }
};

void main()
{
    int j;

 BinarySearchTree<int>*  myTree = new BinarySearchTree<int>();
 myTree->Push( 3 );
 myTree->Push( 5 );
 myTree->Push( 4 );
 myTree->Push( 7 );
 myTree->Push( 2 );
 delete myTree;
 system( "pause" );
}