BST二叉搜索树的实现

编译环境：vc++6.0

 

#include <iostream>
using namespace std;

template<class T>
class BST;

template<class T>
class node
{
    friend void Iterator( node<T>* r);
    friend class BST<T>;
private:
    T data;
    node<T> *lp,*rp;          //左右孩子指针
public:
    node(){lp=rp=NULL;}        //初始化
    node(T d,node<T> *l=NULL,node<T> *r=NULL):data(d),lp(l),rp(r){}
    T getdata(){return data;}
};

template<class T>
class BST
{
    friend void Iterator( node<T>* r);
private:
    node<T> *root;   //树根指针
    int value;
    node<T>* find(const T& x,node<T> *r)
    {
        if(r==NULL)
            return NULL;
        if(x<r->data)
            return find(x,r->lp);
        else if(x>r->data)
            return find(x,r->rp);
        else return r;
    }
    void insert(const T& x,node<T> *&root)
    {
        if(root==NULL)
        {
            root=new node<T>(x);
            cout<<"have inserted "<<x<<endl;
        }
        else if(x<root->data)       
            insert(x,root->lp);
        else if(x>root->data)
            insert(x,root->rp);
        else
            cout<<"the data "<<x<<" has already inserted!"<<endl;    
    }
 
    node<T>*&  min(node<T>* &r)
    {
        if(r->lp!=NULL)
            return min(r->lp);
  
        else return r;
    }
 
    void remove(const T& x,node<T> * &root)
    {
        if(root==NULL)
        {
            cout<<"have not this data "<<x<<endl;
            return;
        }
        else if(x<root->data)                //在左子树中查找
            remove(x,root->lp);
        else if(x>root->data)                 //在右子树中查找
            remove(x,root->rp);
        //找到x值
        else if(root->lp==NULL&&root->rp==NULL)   //删除的节点为叶子节点
        {
            node<T> *q=root;
            root=NULL;
            delete q;           
        }
        else if(root->lp==NULL)               //删除的节点左子树为空
        {
            node<T> *q=root;
            root=root->rp;
            delete q;           
        }
        else if(root->rp==NULL)                 //删除的节点右子树为空
        {
            node<T> *q=root;
            root=root->lp;
            delete q;       
        }
        else            //左右子树都不为空,用该节点的直接先驱节点去替代，然后删除直接前驱节点.                                                                               
        {   node<T> * &p=min(root->rp);
  root->data=p->getdata();
  remove(root->data,p);    
        }
    }
public:
    BST(int v)
    {
        root=NULL;
        cout<<"input the element when "<<v<<" stop"<<endl;
        T x;
        cin>>x;
        while(x!=v)
        {
            insert(x,root);
            cin>>x;
        }
    }
    node<T>* find(const T&x)
    {
        return find(x,root);
    }
   
    void insert(const T& x)
    {
        if(root==NULL)
        {    root->data=x;cout<<"have inserted "<<x<<endl;}
        else insert(x,root);
    }
    node<T> *& min()
    {
        if(root==NULL)
            return NULL;
        return min(root);
    }
   
    void remove(const T& x)    //if lp is null and rp is null,remove it
    {                        //else if lp is null,replace it with its rp;
        if(root==NULL)        //if they are both not null,replace it with the smallest data of rp
        {   
            cout<<"it is null"<<endl;return ;
        }
        remove(x,root);
    }
    node<T>* getroot()
    {
        return root;
    }
};

template<class T>
void Iterator( node<T>* r)// 中序遍历
{
    while(r!=NULL)
    { cout<<r->getdata()<<" ";
 Iterator(r->lp);
 Iterator(r->rp);
 return;
    }
}

int main()
{   
    BST<int> bst(100);
    bst.insert(2);
    bst.insert(3);
    cout<<(bst.find(2))->getdata()<<endl;
    cout<<"the tree is"<<endl;
    Iterator( bst.getroot());
 bst.remove(2);   
 bst.remove(7);
 bst.remove(3);        
    cout<<"/nthe tree is"<<endl;
    Iterator( bst.getroot());
    cin.get();
 
    return 0;
}