数据结构二叉查找树C++实现

#include <iostream>using namespace std;template<class Comparable>class BinarySearchTree{public:    BinarySearchTree();    BinarySearchTree(const BinarySearchTree& rhs); //copy constructor    ~BinarySearchTree(); //destructorpublic:    const Comparable& findMin() const;   //find the minimum value    const Comparable& findMax() const;   //find the maximum value    bool contains(const Comparable& x) const; //Determine whether the tree contains x    bool isEmpty() const;             //Determine whether the tree is empty    void printTree() const;           //print the binary Tree    void makeEmpty();                 //make binary tree empty    void insert(const Comparable& x); //insert a value into binary tree    void remove(const Comparable& x); //remove a value from binary tree    const BinarySearchTree& operator= (const BinarySearchTree& rhs); //overload operator =private:    struct BinaryNode    {        Comparable element;        BinaryNode* left;   //a pointer to left child        BinaryNode* right;   // a pointer to right child        BinaryNode(){}        BinaryNode(const Comparable& theElem, BinaryNode* lt, BinaryNode* rt) : element(theElem), left(lt), right(rt){}//constructor    };             //the binary tree node type    BinaryNode* root; //define the root node    void insert(const Comparable& x, BinaryNode *&t) const;    void remove(const Comparable& x, BinaryNode *&t) const;    BinaryNode* findMin(BinaryNode* t) const;BinaryNode* findMax(BinaryNode* t) const;    bool contains(const Comparable& x, BinaryNode* t) const;    void printTree(BinaryNode* t) const;    void makeEmpty(BinaryNode *&t) const;    BinaryNode* clone(BinaryNode *t) const;};template<class Comparable>BinarySearchTree<Comparable>::BinarySearchTree(){    root = new BinaryNode(); //constructor construct a tree without subtree    root = NULL;}template<class Comparable>BinarySearchTree<Comparable>::BinarySearchTree(const BinarySearchTree& rhs){    root = new BinaryNode();    root = NULL;    makeEmpty();    root = clone(rhs.root);}template<class Comparable>BinarySearchTree<Comparable>::~BinarySearchTree(){    makeEmpty();}template<class Comparable>const Comparable& BinarySearchTree<Comparable>::findMin() const{    return findMin(root)->element;}template<class Comparable>const Comparable& BinarySearchTree<Comparable>::findMax() const{    return findMax(root)->element;}template<class Comparable>bool BinarySearchTree<Comparable>::contains(const Comparable& x) const{    return contains(x, root);}template<class Comparable>bool BinarySearchTree<Comparable>::isEmpty() const{    return root == NULL;}template<class Comparable>void BinarySearchTree<Comparable>::printTree() const{    printTree(root);}template<class Comparable>void BinarySearchTree<Comparable>::makeEmpty(){    makeEmpty(root);}template<class Comparable>void BinarySearchTree<Comparable>::insert(const Comparable& x){    insert(x, root);}template<class Comparable>void BinarySearchTree<Comparable>::remove(const Comparable& x){    remove(x, root);}template<class Comparable>const BinarySearchTree<Comparable>& BinarySearchTree<Comparable>::operator= (const BinarySearchTree& rhs){    if(this != &rhs)    {        makeEmpty();  root = clone(rhs.root);    }    return *this;}template<class Comparable>void BinarySearchTree<Comparable>::insert(const Comparable& x, BinaryNode *&t) const{    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        ;        //do nothing}template<class Comparable>void BinarySearchTree<Comparable>::remove(const Comparable& x, BinaryNode *&t) const{    if (t == NULL)        return;    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) -> element;        remove(t->element, t->right);    }    else    {        BinaryNode *oldNode = t;        t = (t -> left != NULL) ? t -> left : t -> right;        delete oldNode;    }}template<class Comparable>typename BinarySearchTree<Comparable>::BinaryNode* BinarySearchTree<Comparable>::findMin(BinaryNode *t) const{    if(t == NULL)        return NULL;    if(t -> left == NULL)        return t;    return findMin(t -> left);}template<class Comparable>typename BinarySearchTree<Comparable>::BinaryNode* BinarySearchTree<Comparable>::findMax(BinaryNode *t) const{    if(t == NULL)        return NULL;    if(t -> right == NULL)        return t;    return findMax(t -> right);}template<class Comparable>bool BinarySearchTree<Comparable>::contains(const Comparable& x, BinaryNode* t) const{    if(t == NULL)        return false;    else if(x < t -> element)        return contains(x, t -> left);    else if(t -> element < x)        return contains(x, t -> right);    else        return true;}template<class Comparable>void BinarySearchTree<Comparable>::makeEmpty(BinaryNode*& t) const{    if(t != NULL)    {        makeEmpty(t -> left);        makeEmpty(t -> right);        delete t;    }    t = NULL;}template<class Comparable>void BinarySearchTree<Comparable>::printTree(BinaryNode* t) const{    if(t != NULL)    {        printTree(t -> left);        cout << t ->element << "\t";        printTree(t -> right);    }}template<class Comparable>typename BinarySearchTree<Comparable>::BinaryNode* BinarySearchTree<Comparable>::clone(BinaryNode *t) const{    if(t == NULL)        return NULL;    return new BinaryNode(t -> element, clone(t -> left), clone(t -> right));}int main(){    return 0;}