二叉查找树的类模板实现

二叉查找树的性质是，对于树中的每一个结点X，它的左子树中所有的项的值小于X中的项，而它的右子树中所有项的值大于X中的项。

#include <iostream>using namespace std;template <typename T>class BinarySearch{public:    BinarySearch();    BinarySearch ( const BinarySearch & rhs );    ~BinarySearch();    const T &findMin() const;    const T &findMax() const;    bool contains ( const T &x ) const;    bool isEmpty() const;    void printTree() const;    void makeEmpty();    void insert ( const T &x );    void remove ( const T &x );    const BinarySearch &operator= ( const BinarySearch &rhs );private:    struct BinaryNode    {        T element;        BinaryNode *left;        BinaryNode *right;        BinaryNode ( const T & e, BinaryNode *l , BinaryNode *r )            : element ( e ), left ( l ), right ( r ) {}    };    BinaryNode *root; //头结点    void insert ( const T & x, BinaryNode * &t ) ;    void remove ( const T & x, BinaryNode * &t ) ;    const T & findMin ( BinaryNode * t ) const;    const T & findMax ( BinaryNode * t ) const;    bool contain ( const T &x, BinaryNode *t ) const;    void printtree ( BinaryNode *t ) const;    void makeEmpty ( BinaryNode * &t );    BinaryNode *clone ( BinaryNode *t ) const    {        if ( t == NULL )            return NULL;        return new BinaryNode ( t->element, clone ( t->left ), clone ( t->right ) );    }};template<typename T>BinarySearch<T>::BinarySearch(){    root = NULL;}template<typename T>BinarySearch<T>::BinarySearch ( const BinarySearch &rhs ){    root = clone ( rhs.root );}template<typename T>const BinarySearch<T> & BinarySearch<T>::operator= ( const BinarySearch &rhs ){    if ( this != &rhs )    {        makeEmpty();        root = clone ( rhs.root );    }    return *this;}template<typename T>BinarySearch<T>::~BinarySearch(){    makeEmpty();}template<typename T>void BinarySearch<T>::makeEmpty(){    return makeEmpty ( root );}template<typename T>void BinarySearch<T>::makeEmpty ( BinaryNode * &t ){    if ( t != NULL )    {        makeEmpty ( t->left );        makeEmpty ( t->right );        delete t;    }    t = NULL;}template <typename T>void BinarySearch<T>::insert ( const T &x ){    insert ( x, root );}template <typename T>void BinarySearch<T>::insert ( const T &x, BinaryNode * &t ){    if ( t == NULL )        t = new BinaryNode ( x, NULL, NULL );    else if ( x < t->element )        insert ( x, t->left );    else if ( t->element < x )        insert ( x, t->right );    else        ;//x已经存在，不做处理}template <typename T>bool BinarySearch<T>::contains ( const T &x ) const{    return contain ( x, root );}template <typename T>bool BinarySearch<T>::contain ( const T &x, BinaryNode *t ) const{    if ( t == NULL )        return false;    else if ( x < t->element )        return contain ( x, t->left );    else if ( t->element < x )        return contain ( x , t->right );    else        return true;}template <typename T>void BinarySearch<T>::remove ( const T &x ){    remove ( x, root );}template<typename T>void BinarySearch<T>::remove ( const T &x, BinaryNode  * &t ){    if ( t == NULL )        return;    else if ( x < t->element )        remove ( x, t->left );    else if ( t->element < x )        remove ( x, t->right );    else if ( t->left != NULL && t->right != NULL )    {        t->element = findMin ( t->right );        remove ( t->element, t->right );    }    else    {        BinaryNode *old = t;        t = ( t->left != NULL ) ? t->left : t->right;        delete old;    }}template<typename T>const T & BinarySearch<T>::findMax() const{    return findMax ( root );}template<typename T>const T & BinarySearch<T>::findMax ( BinaryNode *t ) const{    if ( t != NULL )        while ( t->right != NULL )            t = t->right;    return t->element;}template<typename T>const T & BinarySearch<T>::findMin() const{    return findMin ( root );}template<typename T>const T & BinarySearch<T>::findMin ( BinaryNode *t ) const{    if ( t == NULL )        return t->element;    if ( t->left == NULL )        return t->element;    return findMin ( t->left );}template<typename T>bool BinarySearch<T>::isEmpty() const{    if ( root == NULL )        return true;    else        return false;}template<typename T>void BinarySearch<T>::printTree() const{    printtree ( root );    cout << endl;}template<typename T>void BinarySearch<T>::printtree ( BinaryNode *t ) const{    /*前序输出*/    //if ( t != NULL )    //    cout << t->element << " ";    //if ( t->left != NULL )    //    printtree ( t->left );    //if ( t->right != NULL )    //    printtree ( t->right );    /*中序输出*/    if ( t->left != NULL )    {        printtree ( t->left );    }    cout << t->element << " ";    if ( t->right != NULL )        printtree ( t->right );    /*后序输出*/    //if(t->left!=NULL)    //    printtree(t->left);    //if(t->right!=NULL)    //    printtree(t->right);    //cout<<t->element<<" ";}