二叉树，删除所有与 pattern匹配的子树

问题遇到的现象和发生背景

删除所有与pattern匹配的子树
BinaryNode*BinaryTree::removeAll(BinaryTree& pattern）

只能删除有一个子树匹配的情况，有多个匹配子树时，无法删除所有匹配子树，无法进行删除

问题相关代码，请勿粘贴截图

//删除子树
template<class T>
void BinaryTree<T>::destroy(BinaryNode<T>*p)  
{
    if (p != NULL)
    {
        destroy(p->left);
        destroy(p->right);
        delete p;
    }

}



//查找根节点
template<class T>
BinaryNode<T>* BinaryTree<T>::searchhead(BinaryNode<T>*q, T key)
{
    BinaryNode<T>*m = NULL;
    if (q != NULL)
    {
        if (q->data == key)
        {
            return q;
        }
        if ((m = searchhead(q->left, key)) == NULL)
            m = searchhead(q->right, key);
    }

    return    m;
}


//查找子树
template<class T>
BinaryNode<T>* BinaryTree<T>::searchone(BinaryTree<T>&bintree)
{
    BinaryNode<T>*p = searchhead(root, bintree.root->data);
    if (p != NULL)
    {
        if (matchtree(p, bintree.root))
            return p;
        else
            return NULL;
    }
    else
        return p;
}


//匹配子树
template<class T>
bool BinaryTree<T>::matchtree(BinaryNode<T>*p, BinaryNode<T>*q)
{
    if (q == NULL&&p == NULL)
        return true;
    if (p == NULL || q == NULL)
        return false;
    if (p->data != q->data)
        return false;
    return(matchtree(p->left, q->left) && matchtree(p->right, q->right));
}


 //删除所有与pattern匹配的子树
template<class T>
BinaryNode<T>*BinaryTree<T>::removeAll(BinaryTree<T>& pattern)//BinaryNode<T>* removeAll(BinaryTree<T> & pattern)
{
    

    BinaryNode<T>*q = searchone(pattern);

    if (q != NULL)
    {
        if(q->left!=NULL)
        {
            destroy(q->left);
            q->left=NULL;
        }
        else
        {
            destroy(q->right);
            q->right=NULL;
        }
    }
    

        

    else
        return NULL;
}

#include "BinaryTree.h"
#include <iostream>
#include <Windows.h>
#include <string>
using namespace std;
int main(){
    char lalist[]="GDBEHFCA"; //GDBGDBEGDBHFCA GDBEHFCA
    char inlist[]="DGBAECHF";//GDBAGDBECGDBHF  DGBAECHF
    char inkey[]="DGB ";
    char lakey[]="GDB";
    BinaryTree<char> tree(lalist,inlist,8);
    BinaryTree<char> pattern(lakey,inkey,3);
    tree.preOrder()  ;
    cout<<endl;
    cout<<"二叉关键子树"<<endl;
     pattern.preOrder() ;
    cout<<endl;
    cout<<"删除后"<<endl;
    tree.removeAll( pattern);
    tree.preOrder() ;
    return 0;
}

运行结果及报错内容

我的解答思路和尝试过的方法

我想要达到的结果

删除所有与 pattern匹配的子树