C ++复制二叉树

Question

If I use this to copy a binary tree

BTNode<ElemType>* BinaryTree<ElemType>::_Copy( BTNode<ElemType>* T){ 
    if (T == NULL){
        return NULL;
    }
    BTNode<ElemType> *p;
    p = new BTNode<ElemType>;
    p->data = T->data;
    p->lchild = _Copy(T->lchild);
    p->rchild = _Copy(T->rchild);
    return p; 
}

and set overload function for = operator like this:

BinaryTree& operator=(const BinaryTree &rhs){
    if (&rhs == this){
        return *this;
    }
    _Destroy (m_root);
    m_root = _Copy ( rhs.m_root);
    return *this;
}

then if I have two treetype element tree_1 and tree_2 .

When I do

tree_2 = tree_1;

I copy all the element from tree_1 to tree_2 . And at this time, I add a new node to tree_2 . The tree_1 will also change. How can I set a new recursive copy function that makes tree_1 remains the same and only change the structure of tree_2 ?

Answer 1

you Overide only the Node Element BTNode = operator

thats way its work for the root copy when you copy the trees [tree_2 = tree_1;]

you are using the defult copy ctor that c++ provide that use bitwise copy(deep copy) you need to create a copy ctor for the tree that use foreach node the" =" operator you allreay implement

node  *Cpy( root ) { 

   if (root == NULL ) : return root;

   node *temp = new node();
   temp->data = root-> data;    

   temp->left = Cpy( root -> left);   

   temp->right = Cpy(root -> right);  

   return temp;
}