C ++二进制搜索树打印和深度计算

Question

I have created binary search tree. My functions can add, delete, and find nodes with numbers. All of that functions is working fine. Can You help me with two functions: 1) Printing BST 2) Calculating depth of BST?

I have no idea how to do this in a quick and easy way. Depth i calculating during adding new Nodes but I want to have function only for doing that.

class Node{
    public:
shared_ptr<Node> right;
shared_ptr<Node> left;
int number;
Node(int number)
{
    this->number=number;
    right=nullptr;
    left=nullptr;
}
~Node()
{
    cout<<"Deleted"<<" "<<number<<endl;
}
};
class BT
{
    public:
    shared_ptr<Node> root;
    int deep;
    BT(int num)
    {
      deep=0;
      root=make_shared<Node>(num);
    }

    void add_number(int num)
    {
        shared_ptr<Node> new_num=make_shared<Node>(num);
        shared_ptr<Node> tmp=root;
        int tmp_deep=0;
        while(tmp!=nullptr)
        {
            tmp_deep++;

            if(tmp->number>num)
            {
            if (tmp->left==nullptr)
            {
                tmp->left=new_num;
                break;
            }

            else
             tmp=tmp->left;
            }

            else if (tmp->number<num)
            {
                if (tmp->right==nullptr)
                 {
                tmp->right=new_num;
                break;
            }
            else
               tmp=tmp->right;
            }


        }
        tmp.reset();
        if (tmp_deep>deep)
            deep=tmp_deep;

    }

    shared_ptr<Node> find_node(int num)
    {
        shared_ptr<Node> tmp=root;

        while (tmp!=nullptr && tmp->number!=num)
        {
           if (tmp->number>num)
            tmp=tmp->left;
            else if (tmp->number<num)
                tmp=tmp->right;

        }

        if (tmp==nullptr)
        {
            cout<<"Not found";
            return nullptr;
        }
        else
            return tmp;

    }

    void delete_ (int num)
    {
        shared_ptr<Node> tmp=root;
        shared_ptr<Node> previous=root;


          while (tmp!=nullptr && tmp->number!=num)
        {
           if (tmp->number>num)
           {
               previous=tmp;
                tmp=tmp->left;

           }

            else if (tmp->number<num)
            {
                previous=tmp;
                tmp=tmp->right;
            }


        }

        if (tmp==nullptr)
        {
            cout<<"Not found";
        }
        else
        {

            if(tmp->left==nullptr && tmp->right==nullptr)
            {

                if (previous->number>tmp->number)
                previous->left=nullptr;
                else
                previous->right=nullptr;


                tmp.reset();
            }
            else if (tmp->left==nullptr && tmp->right!=nullptr)
            {
                if(tmp->right!=nullptr)
                {
                 previous->right=tmp->right;
                }
                else
                    previous->right=tmp->left;
                tmp.reset();
            }
            else if (tmp->left!=nullptr && tmp->right==nullptr)
            {
                if(tmp->right!=nullptr)
                {
                 previous->left=tmp->right;
                }
                else
                    previous->left=tmp->left;
                tmp.reset();
            }
            else if (tmp->left!=nullptr && tmp->right!=nullptr)
            {

                shared_ptr<Node> tmp_left=tmp->right;
                shared_ptr<Node> prev_left=tmp->right;
               while (tmp_left->left!=nullptr)
               {

                        //prev_left=tmp_left;
                        tmp_left=tmp_left->left;


                }
                if (tmp->number<previous->number)
                    previous->left=tmp_left;
                else
                    previous->right=tmp_left;

            prev_left->left=tmp_left->right;
            tmp_left->left=tmp->left;
            tmp_left->right=tmp->right;
            tmp.reset();

            }




        }

        void show_bt()
        {

        }
        void calc_depth()
        {

        }

    }




};

Answer 1

Both of calculating depth and printing can done using tree traversal . Moreover, tree traversal has O(n) time complexity( n is number of nodes in the tree).

PS: For calculating tree depth you can use one of three traversal methods .

1. In each recursion call increase the depth variable
2. After that decrease it and
3. Save total maximum value(before decreasing it)

Answer 2

This exercise is something every programmer has to do, to learn recursion . This can also be done by iteration , but that requires to build your stack

For recursion, a function has to be created, which calls itself in order to "calculate" a result.

You have to think, how the end result can be "calculated" from smaller results.

Let's look at the depth calculation.

This is on a tree. Which is constructed from nodes.

So how can we calculate something on the nodes to get the end result?

Every node has a height which is 1 greater than the maximum of height of (the left subtree and, right subtree). If there is no subtree we'll just say it has a height of zero.

BTW: never look for the quick and easy in the beginning. Always the first step is: make it work.