#include <iostream>
#include <set>

/******************************************************
 * A container is an object whose purpose is to store
 * and organize a collection of values.
 *
 * The C++ Standard Library provides several container
 * classes. One of these is std::set.
 *
 * A std::set stores a collection of unique values in
 * sorted order. If you insert the same value more than
 * once, only one copy is stored.
 *
 * For example,
 *
 *     std::set<int> data{};
 *
 * creates an empty set that stores integers.
 *
 * We interact with a set using member functions:
 *
 *     data.insert( value );  // Insert a value
 *     data.size();           // Number of values
 *     data.count( value );   // 1 if present, 0 otherwise
 *     data.erase( value );   // Remove a value
 *     data.begin();          // Iterator to first value
 *     data.end();            // Iterator past last value
 *
 * Notice the syntax:
 *
 *     object.member_function( arguments )
 *
 * The member functions control how we access and
 * modify the values stored in the container.
 ******************************************************/

// Function declaration
int main();

// Function definition
int main() {
  // Create an empty set that stores integers.
  std::set<int> data{};

  // 100 random integers
  int random[100]{
    26, 61, 15,  2, 86,
     1, 32, 37, 91, 73,
    97,  5,  9, 20, 56,
    70, 89, 18, 99, 24,
    64, 79, 77, 37, 50,
    76, 65, 49,  7, 94,
     4,  1, 86,  8, 60,
    19, 99, 63, 38, 94,
    76, 49, 62, 37, 85,
    28,  4, 21,  8, 39,
    61,  6, 79,  6,  1,
    91, 84, 44, 39, 39,
    68, 28, 86, 92, 86,
     3, 56, 64, 14, 42,
    32, 59, 38, 50, 28,
    92, 52, 84, 64, 90,
    82, 44, 78, 39, 24,
     0, 94, 46, 49, 75,
    32, 19,  3, 46, 71,
     0, 59, 29, 47, 16
  };

  // insert(...) adds a value to the set. Duplicate
  // values are ignored.
  for ( std::size_t k{0}; k < 100; ++k ) {
    data.insert( random[k] );
  }

  // size() returns the number of values in the set.
  std::cout << "The size of 'data' is "
            << data.size() << std::endl;

  int delete_count{0};

  for ( int k{3}; k < 100; k += 13 ) {
    // count(...) returns 1 if the value is in the set
    // and 0 otherwise.
    std::cout << "Erasing " << k << " which has count "
              << data.count( k ) << std::endl;

    // erase(...) removes the value and returns the number
    // of entries removed: either 0 or 1 for a set.
    delete_count += data.erase( k );
  }

  std::cout << delete_count << " entries were deleted"
            << std::endl;

  std::cout << "The size of 'data' is now "
            << data.size() << std::endl;

  // begin() returns an iterator to the first value and
  // end() represents the position just past the last.
  //
  // The values appear in sorted order.
  for ( std::set<int>::iterator itr{ data.begin() };
        itr != data.end(); ++itr ) {
    std::cout << *itr << " ";
  }

  std::cout << std::endl;

  return 0;
}