Program for creating a binary tree,traversals, etc

#include<iostream>
#include<cstdlib>
#include<queue>
#include<cmath>
using namespace std;
class node
{
 public:
  
  int data;
  node *left;
  node *right;
};
class tree : public node
{
 public:
  int n,value;
  node *root;
     tree()  // constructor of tree for intialising the values
   {
    
    int q=0,m;
    cout<<"\nenter the no.of levels : ";
    cin>>m;
    node *p=new node;
    p->left=p->right=NULL;
    root=p;
    
    queue<node*> Q;
    Q.push(p);
    while(!Q.empty())
    {
     if(q<(pow(2,m)-1))
     {
       node *current;
       current = Q.front();
       Q.pop();
       cin>>current->data;
       q++;
       if(q<pow(2,m-1))
       {
        node *a=new node;  a->left=a->right=NULL; current->left=a;
        node *b=new node;  b->left=b->right=NULL; current->right=b;
        Q.push(current->left);
        Q.push(current->right);
       }
       
     }
     else
     {
      break;
     }

    }
   }
   
  void pretrvsal()
   {
    preorder(root);
   }
   
  void preorder(node *root)
   {
    if(root==NULL)
    {
     return ;
    }
    cout<<" "<<root->data<<" ";
    preorder(root->left);
    preorder(root->right);

   }
   
  void posttrvsal()
   {
    postorder(root);
   }

  void postorder(node *root)
   {
    if(root==NULL)
    {
     return ;
    }

    postorder(root->left);
    postorder(root->right);
    cout<<" "<<root->data<<" ";

   }
   
  void intrvsal()
   {
    inorder(root);
   }

  void inorder(node *root)
   {
    if(root==NULL)
    {
     return ;
    }

    inorder(root->left);
    cout<<" "<<root->data<<" ";
    inorder(root->right);

   }
   
   void levelorder()
   {
    if(root == NULL)
    return;
    
    queue<node*> Q;
    Q.push(root);
    while(!Q.empty())
    {
     node* current = Q.front();
     Q.pop();      // removing the element at front
     cout<<" "<<current->data<<" ";
     if(current->left != NULL) Q.push(current->left);
     if(current->right != NULL) Q.push(current->right);
    }
   }
  
   void level()
   {
    cout<<"enter the level : ";
    cin>>n;
    int a=1;
    if(root == NULL)
     return;
    queue<node*> Q;
    Q.push(root);
    while(!Q.empty())
    {
     node* current = Q.front();
     Q.pop();
     if(a>=pow(2,n) && a<pow(2,n+1))    // removing the element at front
     cout<<" "<<current->data<<" ";a++;
     if(current->left != NULL) Q.push(current->left);
     if(current->right != NULL) Q.push(current->right);
    }
   }
   
  
   void find()
   {
    cout<<"enter the key : ";
    cin>>n;
    int a=1,b=0;
    if(root == NULL)
    return;

    queue<node*> Q;
    Q.push(root);
    while(!Q.empty())
    {
     node* current = Q.front();
     Q.pop();
     if(n==current->data)
     {
      cout<<"the key is found at node : "<<a;
      b=1;
     }
     a++;
     if(current->left != NULL) Q.push(current->left);
     if(current->right != NULL) Q.push(current->right);
    }
    if(b==0)
    {
     cout<<"\nthe element is not found\n";
    }
   }
};

int main()
{
 int choice,a;

        tree tr;
        
        while (1)

        {

            cout<<endl<<"\tBINARY TREE"<<endl;

            cout<<"1.preorder"<<endl;

            cout<<"2.postorder"<<endl;

            cout<<"3.inorder"<<endl;
            
            cout<<"4.levelorder"<<endl;
            
            cout<<"5.keys at level"<<endl;
            
            cout<<"6.find node for key"<<endl;

            cout<<"7.Exit "<<endl;

            cout<<"\nEnter your choice : ";

            cin>>choice;

            switch(choice)

            {

            case 1:


                tr.pretrvsal();

                cout<<endl;

                break;

            case 2:


                tr.posttrvsal();

                cout<<endl;

                break;

            case 3:


                tr.intrvsal();

                cout<<endl;

                break;

     case 4:
                
                
  tr.levelorder();
                
                cout<<endl;
                
                break;
                
     case 5:
    
    
                tr.level();

                cout<<endl;

                break;
                
                 
     case 6:


                tr.find();

                cout<<endl;

                break;
                
     case 7:
    
  exit(0);
                
     default:
    
              break;
  }
 }
            
return 0;
}