// This ensures that this file is included at most once
// in any program, as there may be multiple include
// statements.
#pragma once

#include <cstddef>

  ///////////////////////
 // Class declaration //
///////////////////////

class Pair;

  //////////////////////
 // Class definition //
//////////////////////

// Store a pair of indices.
class Pair {
  public:
    std::size_t first_;
    std::size_t second_;
};


// Note: The C++ standard library already provides a class
// called std::pair in the <utility> library. Unlike our Pair
// class, std::pair uses templates, allowing the two stored
// values to have specified, and possibly different, types.
//
// For example,
//
//     std::pair<std::size_t, std::size_t> p{ 3, 7 };
//
// creates a pair containing two std::size_t values. The two
// values are accessed using the member variables 'first'
// and 'second', rather than 'first_' and 'second_':
//
//     p.first
//     p.second
//
// You will learn about templates in upper-year courses,
// but in essence, they allow you to write, for example,
// an array class for which the user can specify the type
// of the entries in the array. In this case, templates
// allow the user to specify the types of both items
// stored in the pair:

/*
template <typename T, typename U>
class Pair {
    public:
        T first;    // The first type
        U second;   // The second type
};

int main() {
    Pair<int, double> p{ 3, 4.5 };

    std::cout << p.first << std::endl;   // 3
    std::cout << p.second << std::endl;  // 4.5

    return 0;
}
*/