Hashing-Quadratic probing

//this is a hacker rank code for a problem using qudratic hashing 

#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <array>
using namespace std;
void print_data(int a[],int n);
void insert_data(int a[],int data,int n);
void delete_data(int a[],int data,int n);
void search(int a[],int data,int n);
int probe=0;

int main() {
    int n,q,ch,data;
    cin>>n>>q;
    int a[n];
    for(int i=0;i<n;i++)
        a[i]=0;
    for(int i=0;i<q;i++)
    {
        cin>>ch;
        switch(ch)
        {
            case 1:cin>>data;
                insert_data(a,data,n);
                break;
            case 2:cin>>data;
                probe=0;
                search(a,data,n);
                cout<<probe+1<<endl;
            break;
            case 3:cin>>data;
                delete_data(a,data,n);
                break;
            case 4:print_data(a,n);
                cout<<endl;
        }
    }
    return 0;
}
void insert_data(int a[],int data,int n)
{
    int index,i=0;
    index=data % n;
    while(a[index]!=0 && a[index]!=-1 )
    {
        i++;
        index=(data%n+i*i)%n;
    }
    a[index]=data;
}

void print_data(int a[],int n)
{
    for(int i=0;i<n;i++)
        if(a[i]==0 or a[i]==-1)
            cout<<"NULL ";
        else cout<<a[i]<<" ";
}
void delete_data(int a[],int data,int n)
{
    int index,i=0;
    index=data % n;
    while(a[index]!=data)
    {
        i++;
        index=(data%n+i*i)%n;
    }
    a[index]=0;
}
void search(int a[],int data,int n)
{
    int index,i=0;
    index=data % n;
    while(a[index]!=data)
    {       
        probe++;
        i++;
        index=(data%n+i*i)%n;
    }
}