二叉排序树的c++实现，查找，删除等

#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;
}