Diameter of a binary tree

#include<iostream>
using namespace std;

class Node{
  public:
      int data;
      Node *left,*right;
      Node(int key){
        data=key;
        left=NULL;
        right=NULL;
        }
  };

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

int Height(Node *node_ptr){
  if(node_ptr==NULL)
    return 0;
  return 1+max(Height(node_ptr->left),Height(node_ptr->right));
  }

int DiameterOfTree(Node * root){
  if(root==NULL)
   return 0;
   return max(1+Height(root->left)+Height(root->right),max(DiameterOfTree(root->left),DiameterOfTree(root->right)));
  }

int main(){
  Node *root=NULL;
  Node *newnode=new Node(1);
  root=newnode;
  root->left=new Node(2);
  root->right=new Node(3);
  (root->left)->left=new Node(4);
  (root->left)->right=new Node(5);
  cout<<"pre order traversal ";
  preorder(root);
  cout<<endl<<DiameterOfTree(root);
  return 0;
  }