二叉排序树的c++实现
完整代码和测试在我的github:https://github.com/yqtaowhu

#pragma once
template <typename T>
struct BSTNode
{
    T m_nValue;
    BSTNode *m_pLeft;
    BSTNode *m_pRight;
};
template <typename T>
class BST
{
public:
    BST(T r[],int n);
    void InsertBST(BSTNode<T> *&R, BSTNode<T> *s);//插入数据在BST,R根结点，插入结点s
    BSTNode<T> *Search(BSTNode<T> *r, T key);
    bool DeleteBST(BSTNode<T>*&R, T key);//删除key
    void Delete(BSTNode<T>*&R);
    BSTNode<T> * GetpRoot();
private:
    BSTNode <T> *root;

};
template <typename T>
void BST<T>::InsertBST(BSTNode<T> *&R, BSTNode<T> *s)
{
    if (R == nullptr)
        R = s;//R为空，将s直接插入
    else if (s->m_nValue < R->m_nValue)
        InsertBST(R->m_pLeft, s);//递归向左子树中插入
    else
        InsertBST(R->m_pRight, s);

}
//构造BST的过程即是一个反复插入的过程
template <typename T>
BST<T>::BST(T r[], int n)
{
    root = nullptr;
    for (size_t i = 0; i < n; i++)
    {
        BSTNode<T> *s = new BSTNode<T>;
        s->m_nValue = r[i];
        s->m_pLeft= nullptr;
        s->m_pRight = nullptr;
        InsertBST(root, s);//插入
    }
}
template <typename T>
BSTNode<T>* BST<T>::Search(BSTNode<T> *r, T key)
{
    if (r == nullptr)
        return nullptr;
    if (key == r->m_nValue)
        return r;
    else if (r->m_nValue > key)
        return Search(r->m_pLeft, key);
    else
        return Search(r->m_pRight, key);
}
template <typename T>
bool BST<T>::DeleteBST(BSTNode<T>*&R, T key)
{
    if (R == nullptr)
        return false;
    else if (R->m_nValue == key)
    {
        Delete(R);
        return true;
    }
    else if (key < R->m_nValue)
        return DeleteBST(R->m_pLeft, key);//查找key值
    else
        return DeleteBST(R->m_pRight, key);
}
//删除情况分为三种情况
//仔细理解
template <typename T>
void BST<T>::Delete(BSTNode<T>*&R)
{
    BSTNode<T>*q, *s;
    if (R->m_pLeft==nullptr)//如果其左子树为空
    {
        q = R;
        R = R->m_pRight;//R的右子数赋给R
        delete q;//删除q,即以前的R
    }
    if (R->m_pRight==nullptr)
    {
        q = R;
        R = R->m_pLeft;
        delete q;
    }
    else//左右子数都在
    {
        q = R; s = R->m_pLeft;
        //寻找最大值进行与根结点的替换
        while (s->m_pRight!=nullptr)
        {
            q = s;
            s = s->m_pRight;
        }
        R->m_nValue = s->m_nValue;//将此最大值赋给要删除的节点
        if (q != R)//即进行了while循环，改变q
            q->m_pRight = s->m_pLeft;//s是q的右孩子，s是没有右子数的
        else
            R->m_pLeft = s->m_pLeft;
        delete s;
    }
}
//获得根指针
template <typename T>
 BSTNode<T> * BST<T> ::GetpRoot()
{
    return root;
}