Найти НОД четырех натуральных чисел

#include <iostream>
#include <vector>
 
unsigned int get_arr_size_from_user()
{
    std::cout << "Enter your array size: ";
    unsigned int arr_size;
    std::cin >> arr_size;
    return arr_size;
}
 
template <typename T>
void fill_by_user( T & arr )
{
    for ( auto & elem : arr )
    {
        std::cout << "Enter a value: ";
        std::cin >> elem;
    }
}
 
template <typename T1, typename T2>
void show( const T1 & message, const T2 & arr )
{
    std::cout << message;
    for ( const auto & elem : arr )
        std::cout << elem << " ";
    std::cout << "\n";
}
 
int main()
{
    std::vector<int> ivec( get_arr_size_from_user() );
    fill_by_user( ivec );
    show( "\nThis is your array: ", ivec );
}

#include <iostream>
 
unsigned int get_arr_size_from_user()
{
    std::cout << "Enter your array size: ";
    unsigned int arr_size;
    std::cin >> arr_size;
    return arr_size;
}
 
void fill_by_user( int * arr, unsigned int arr_size )
{
    for ( unsigned int i = 0; i < arr_size; ++i )
    {
        std::cout << "Enter a value: ";
        std::cin >> arr[i];
    }
}
 
void show( const char * message, int * arr, unsigned int arr_size )
{
    std::cout << message;
    for ( unsigned int i = 0; i < arr_size; ++i )
        std::cout << arr[i] << " ";
    std::cout << "\n";
}
 
int main()
{
    unsigned int arr_size = get_arr_size_from_user();
 
    int * arr = new int[arr_size];
    fill_by_user( arr, arr_size );
    show( "\nThis is your array: ", arr, arr_size );
    delete [] arr;
}

#include <iostream>
 
unsigned int get_number_from_user( const char * message )
{
    std::cout << message;
    unsigned int arr_size;
    std::cin >> arr_size;
    return arr_size;
}
 
void fill_by_user( int * arr, const unsigned int arr_size )
{
    for ( unsigned int i = 0; i < arr_size; ++i )
    {
        std::cout << "Enter a value of " << i + 1 << " element: ";
        std::cin >> arr[i];
    }
}
 
void show( const char * message, const int * const arr, const unsigned int arr_size )
{
    std::cout << message;
    for ( unsigned int i = 0; i < arr_size; ++i )
        std::cout << arr[i] << " ";
    std::cout << "\n";
}
 
int main()
{
    unsigned int arr_size = get_number_from_user( "Enter your array size: " );
 
    int * arr = new int[arr_size];
    fill_by_user( arr, arr_size );
    show( "\nThis is your array: ", arr, arr_size );
    delete [] arr;
}

#include <iostream>
 
unsigned int get_number_from_user( const char * message )
{
    std::cout << message;
    unsigned int arr_size;
    std::cin >> arr_size;
    return arr_size;
}
 
void fill_by_user( int * arr, const unsigned int arr_size )
{
    for ( unsigned int i = 0; i < arr_size; ++i )
    {
        std::cout << "Enter a value of " << i + 1 << " element: ";
        std::cin >> arr[i];
    }
}
 
void show( const char * message, const int * const arr, const unsigned int arr_size )
{
    std::cout << message;
    for ( unsigned int i = 0; i < arr_size; ++i )
        std::cout << arr[i] << " ";
    std::cout << "\n";
}
 
void show( const char * message, const int number )
{
    std::cout << message << number;
}
 
int find_greatest_common_divisor( const int * const arr, const unsigned int arr_size )
{
    int greatest_common_divisor = 0;
    
    // TODO: implement this function
    
    return greatest_common_divisor;
}
 
int main()
{
    unsigned int arr_size = get_number_from_user( "Enter your array size: " );
 
    int * arr = new int[arr_size];
    fill_by_user( arr, arr_size );
    show( "\nThis is your array: ", arr, arr_size );
    show( "\nGreatest common divisor: ", find_greatest_common_divisor( arr, arr_size ) );
    delete [] arr;
}

// вместо такого варианта:
int find_greatest_common_divisor( const int * const arr, const unsigned int arr_size )
{
    int greatest_common_divisor = 0;
    
    // TODO: implement this function
    
    return greatest_common_divisor;
}
 
// сделайте так:
int find_greatest_common_divisor( int * arr, const unsigned int arr_size )
{
    int greatest_common_divisor = 0;
    
    // TODO: implement this function
    
    return greatest_common_divisor;
}