task 4( ds lab 7) 3rd sem

#include<bits/stdc++.h>
using namespace std;
int y;
struct node
{
    int data;
    struct node* left;
    struct node* right;
};
typedef struct node Node;
Node* create_node(int item)
{
    Node* new_node=new Node();
    if(new_node==NULL)
        cout<<"Error"<<endl;
    else
    {
        new_node->data=item;
        new_node->left=new_node->right=NULL;
    }
    return new_node;
}
Node* insert_key(Node* x,int key)
{
    Node* new_node=create_node(key);
    if(x==NULL)
        return new_node;
    if(key>x->data)
    {
        x->right=insert_key(x->right,key);
    }
    else if(key<x->data)
    {
        x->left=insert_key(x->left,key);
    }
    return x;
}
Node * findmin(Node* node)
{
    struct node* current = node;
    while (current && current->left != NULL)
        current = current->left;

    return current;
}
Node * findmax(Node* node)
{
    Node* current = node;
    while (current && current->right != NULL)
        current = current->right;

    return current;
}
void find_pre_suc(Node* root, Node*& pre, Node*& suc, int val)
{
    if (root == NULL)
        return ;
    if (root->data == val)
    {
        Node* temp;
        if (root->left != NULL)
        {
            temp = root->left;
            pre = findmax(temp) ;
        }
        if (root->right != NULL)
        {
            temp = root->right ;
            suc = findmin(temp) ;
        }
        return ;
    }
    if (root->data>val)
    {
        suc = root ;
        find_pre_suc(root->left, pre, suc, val) ;
    }
    else
    {
        pre = root ;
        find_pre_suc(root->right, pre, suc, val) ;
    }
}

bool find_node(Node* node, int val)
{
    if (node == NULL)
        return false;
    if (node->data == val)
        return true;
    if(find_node(node->left,val))
          return true;
    else
        return find_node(node->right,val);
}

int main()
{

    Node* root=NULL;
    while(1)
    {
        int n;
        cin>>n;
        y=1;
        if(n!=-1)
            root=insert_key(root,n);
        else
            break;
    }
    int k;
    cout<<"Number of test-cases"<<endl;
    cin>>k;
    for(int j=0; j<k; j++)
    {
        int p;
        cin>>p;
        if(find_node(root,p)==false)
            cout<<"Reservation not found!"<<endl;
        else
        {
            Node* pre = NULL, *suc = NULL;
            find_pre_suc(root,pre,suc,p);
            if (pre != NULL)
                cout << pre->data <<" ";
            else
                cout << "NULL" <<" ";
            if (suc != NULL)
                cout << suc->data <<" ";
            else
                cout << "NULL" <<" ";
            cout<<endl;
        }
    }
}