Find ceil and floor of a key in BST

findceilfloor.cpp

#include<iostream>
#include<cstdlib>
using namespace std;

struct node{
int data;
struct node *left;
struct node *right;
};

struct node *newnode(int x)
{
 struct node* ptr=(struct node*)malloc(sizeof(struct node));
    ptr->data=x;
    ptr->left=NULL;
    ptr->right=NULL;
    return ptr;
}

struct node* insert(struct node *root,int x)
{

struct node* par;
    if(root==NULL)
    {
        root=newnode(x);
        return root;
    }
    else
    {
        struct node *proot=root;
        while(proot!=NULL)
        {

            if(x<proot->data)
            {
                par=proot;
                proot=proot->left;

            }
            else
            {
                par=proot;
                proot=proot->right;

            }
        }
         if(x<par->data)
        par->left=newnode(x);
    else
        par->right=newnode(x);

        return root;
    }

}

void display(struct node *root)
{

    if(root==NULL)
        return;
    display(root->left);
    cout<<"\t"<<root->data;
    display(root->right);
}
void findceilfloor(struct node *root,int &ceil,int &floor,int key)
{
    if(root==NULL)
      return;

    if(root->data==key)
    {
        ceil=root->data;
        floor=root->data;
    }
    if(key<root->data)
    {
        ceil=root->data;
        findceilfloor(root->left,ceil,floor,key);
    }
    if(key>root->data)
    {
        floor=root->data;
        findceilfloor(root->right,ceil,floor,key);
    }


}
int main()
{

    int x,key;
    int ceil=-1,floor=-1;
    struct node *root=NULL;
        while(1)
        {

            cin>>x;
            if(x==-1)
            break;

            root=insert(root,x);
        }

        display(root);
        cout<<endl;
        cin>>key;
        findceilfloor(root,ceil,floor,key);
        cout<<"\n ceil is "<<ceil<<" and floor is"<<floor;
}