main.cpp

#include <iostream>
#include <vector>
#include <cmath>
#include <fstream>
#include <string>
#include <algorithm>

using namespace std;

int main()
{
  // Declare variables
  // Whether or not to run in debug mode
  bool debug = true;
  // Numerical identifier for which apportionment method to use
  unsigned int method;
  // The .CSV file which will contain the input data
  ifstream input_file;
  // Pull from the data directory
  string data_name = "data/";
  // The name of the input file
  string input_name;
  // The .CSV file which will contain the output data
  ofstream output_file;
  // The name of the output file
  string output_name;
  // Vector of the population of each state
  vector<unsigned int> pop_vector;
  // Vector of the seats belonging to each state
  vector<unsigned int> seat_vector;
  // Vector of the names of each state
  vector<string> name_vector;
  // Vector of the lines from the input file
  vector<string> line_vector;
  // String storing a line from the input file
  string line;
  // Opening prompts for users
  cout << "This program relies on user input to specify specific parameters\n";
  cout << "If invalid values are entered, the program will terminate and need to be restarted\n";
  cout << "Hope you enjoy it :)\n\n";

  // First specify apportionment method
  cout << "Enter the number corresponding to the apportionment method you want to use\n\n";
  cout << "1: Huntington-Hill method\n";
  cout << "2: Hamilton method\n";
  cout << "3: Jefferson method\n";
  cout << "4: Webster method\n";
  cout << '\n';
  cout << "Please enter a number between 1 and 4:\n\n";
  cin >> method;
  cout << '\n';
  if (method == 1)
    cout << "Huntington-Hill method selected\n\n";
  else if (method == 2)
    cout << "Hamilton method selected\n\n";
  else if (method == 3)
    cout << "Jefferson method selected\n\n";
  else if (method == 4)
    cout << "Webster method selected\n\n";
  else
  {
    cout << "ERROR: Invalid input of " << method << " entered, closing program\n";
    return 0;
  }
  cout << "What is the name of the data file (in .csv format)?\n\n";

  cin >> input_name;
  input_name = data_name.append(input_name);
  input_file.open(input_name);

  cout << '\n';

  if (input_file.is_open())
  {
    if (debug)
      cout << input_name << " was successfully opened\n\n";
    while (getline(input_file, line))
		{
			line_vector.push_back(line);
		}
    input_file.close();
  }
  else
  {
    cout << "ERROR: Could not open " << input_name << ". Closing the program\n";
    return 0;
  }
  // Parse the .csv input file
  for (unsigned int i = 0; i < line_vector.size(); ++i)
	{
		string to_parse = line_vector[i];
		string delimeter = ",";
		string name = to_parse.substr(0, to_parse.find(delimeter));
		to_parse.erase(0, to_parse.find(delimeter) + 1);
		unsigned int pop = stoi(to_parse);
		name_vector.push_back(name);
		pop_vector.push_back(pop);
	}

  // Total population
  unsigned int population = 0;
  for (unsigned int i = 0; i != pop_vector.size(); ++i)
		population += pop_vector[i];
  // The total number of seats to apportion
  unsigned int total_seats = 0;
  // The ideal number of people per seat
  unsigned int ideal_ratio = 0;
  cout << "Would you prefer to specify (enter the number corresponding to that option)?\n\n";

  cout << "1: The total number of seats to be apportioned (recommended for Hamilton & Huntington-Hill)\n";
  cout << "2: The ideal number of people per seat (recommended for Jefferson & Webster)\n";

  // Whether to use total seats or people per seat
  unsigned int option;

  cin >> option;

  cout << '\n';

  // Ideal number of people per seat
  double ratio = 0.0;
  if (option == 1)
  {
    cout << "How many total seats will there be to apportion?\n\n";
    cin >> total_seats;
    cout << '\n';
    if (total_seats == 0)
    {
      cout << "ERROR: There cannot be zero seats to apportion\n";
      return 0;
    }
    else if (total_seats < name_vector.size())
    {
      cout << "ERROR: There cannot be " << total_seats
           << " total seats since that is less than the number of states which is "
           << name_vector.size() << '\n';
      return 0;
    }
    ratio = population / total_seats;
  }
  else if (option == 2)
  {
    cout << "How many people should there be per seat?\n\n";
    cin >> ideal_ratio;
    cout << '\n';
    if (ideal_ratio >= population)
    {
      cout << "ERROR: People per seat ratio of " << ideal_ratio << " specified when total population is " << population << '\n';
      return 0;
    }
    else if (ideal_ratio >= population / pop_vector.size())
      cout << "WARNING: People per seat ratio of " << ideal_ratio << " is greater than the total population divided by the number of states" << "\n\n";
  }

  // Total number of seats that have been assigned
  unsigned int assigned_seats = 0;

  // Every state gets 1 seat initially
  // That's the rule in the US Constitution and is honestly a good rule in general
  for (unsigned int i = 0; i != pop_vector.size(); ++i)
  {
    seat_vector.push_back(1);
    assigned_seats++;
  }
  // You could probably use a switch but if/else if statements work so...
  // Method 1: The Huntington-Hill method
  if (method == 1)
  {
    // Calculated representation
    double hh_ratio = 0.0;
    // Index of the state with the highest underrepresentation ratio
    unsigned int hh_ratio_index = 0;
    // If ratio was specified, calculate total_seats from the ratio
    if (option == 2)
      total_seats = population / ideal_ratio;
    while (assigned_seats < total_seats)
    {
      for (unsigned int i = 0; i != pop_vector.size(); ++i)
  		{
  			double in_ratio = pop_vector[i] / pow((seat_vector[i] * (seat_vector[i] + 1)), 0.5);

  			if (in_ratio > hh_ratio)
  			{
  				hh_ratio = in_ratio;
  				hh_ratio_index = i;
  			}
  		}
  		seat_vector[hh_ratio_index] = seat_vector[hh_ratio_index] + 1;
  		hh_ratio = 0.0;
  		assigned_seats++;
    }
    if (assigned_seats > total_seats)
      cout << "WARNING: Allocated Huntington-Hill method with " << assigned_seats << " instead of " << total_seats << "\n\n";
  }
  // Method 2: The Hamilton method
  else if (method == 2)
  {
    // Calculated representation
    double h_ratio = 0.0;
    // Index of the state with the highest underrepresentation ratio
    unsigned int h_ratio_index = 0;
    // If ratio was specified, calculate total_seats from the ratio
    if (option == 2)
      total_seats = population / ideal_ratio;
    while (assigned_seats != total_seats)
    {
      for (unsigned int i = 0; i != pop_vector.size(); ++i)
  		{
  			double in_ratio = pop_vector[i] / ratio;
  			in_ratio -= static_cast<double>(seat_vector[i]);

  			if (in_ratio > h_ratio)
  			{
  				h_ratio = in_ratio;
  				h_ratio_index = i;
  			}
  		}
  		seat_vector[h_ratio_index] = seat_vector[h_ratio_index] + 1;
  		h_ratio = 0.0;
  		assigned_seats++;
    }
  }
  // Method 3: The Jefferson method
  else if (method == 3)
  {
    unsigned int j_threshold = 0;
    if (option == 1)
    {
      // Number of times the while loop is performed
      unsigned int num_jefferson_loops = 0;
      j_threshold = population / total_seats;
      while (assigned_seats < total_seats)
      {
        num_jefferson_loops++;
        for (unsigned int i = 0; i != pop_vector.size(); ++i)
          if (pop_vector[i] > j_threshold)
            seat_vector[i] = pop_vector[i] / j_threshold;
          assigned_seats = 0;
          for (unsigned int i = 0; i != pop_vector.size(); ++i)
            assigned_seats += seat_vector[i];
          if (assigned_seats > total_seats)
            cout << "WARNING: Allocated Jefferson method with " << assigned_seats << " instead of " << total_seats << "!\n\n";
          else if (assigned_seats < total_seats && j_threshold == 1)
          {
            cout << "ERROR: Cannot allocate Jefferson method with given inputs, closing program\n";
            return 0;
          }
          else
          {
            if (debug)
              cout << "Recalculating Jefferson method\n\n";
            // Reduce the threshold by 1% and then recalculate
            // This may need to be adjusted in the future
            j_threshold = j_threshold - (j_threshold * 0.01);
        }
      }
      if (debug)
        cout << "Required " << num_jefferson_loops << " loops\n\n";
    }
    else if (option == 2)
    {
      j_threshold = ideal_ratio;
      assigned_seats = 0;
      for (unsigned int i = 0; i != pop_vector.size(); ++i)
      {
        if (pop_vector[i] > ideal_ratio)
          seat_vector[i] = pop_vector[i] / ideal_ratio;
        assigned_seats += seat_vector[i];
      }
    }
  }
  // Method 4: The Webster method
  else if (method == 4)
  {
    double webster_seats = 0.0;
    assigned_seats = 0;
    for (unsigned int i = 0; i != pop_vector.size(); ++i)
    {
      if (option == 1)
        if (pop_vector[i] > ratio)
        {
          webster_seats = pop_vector[i] / ratio;
          seat_vector[i] = round(webster_seats);
        }
      else if (option == 2)
        if (pop_vector[i] > ideal_ratio)
        {
          webster_seats = pop_vector[i] / ideal_ratio;
          seat_vector[i] = round(webster_seats);
        }
      assigned_seats += seat_vector[i];
    }
    // There is the possibility of not being able to match the specified number of seats with the Webster method
    if (option == 1 && assigned_seats != total_seats)
      cout << "WARNING: Allocated Webster method with " << assigned_seats << " instead of " << total_seats << "!\n";
  }

  cout << "What is the name of the output file (please end it with the .csv extension)?\n\n";

  cin >> output_name;

  output_file.open(output_name);

  output_file << "Name,Population,Seats\n";
  for (unsigned int i = 0; i != pop_vector.size(); ++i)
	{
		output_file << name_vector[i] << ","
					<< pop_vector[i] << ","
					<< seat_vector[i] << '\n';
	}
	output_file << "Total," << population << "," << assigned_seats << '\n';
	output_file.close();

  return 0;
}