house.rb

#!/usr/bin/ruby
# Calculate the number of seats to apportion for each state in the union.
# This script is based on the algorithm described at https://www.census.gov/population/apportionment/about/computing.html

def largest_hash_key(hash)
  hash.max_by{|k,v| v}[0]
end

def get_multiplier(n)
  return 1/(n*(n-1)**0.5)
end

states = [ 'AK', 'AL', 'AR', 'AZ', 'CA', 'CO', 'CT', 'DC', 'DE', 'FL', 'GA', 'HI', 'IA', 'ID', 'IL', 'IN', 'KS', 'KY', 'LA', 'MA', 'MD', 'ME', 'MI', 'MN', 'MO', 'MS', 'MT', 'NC', 'ND', 'NE', 'NH', 'NJ', 'NM', 'NV', 'NY', 'OH', 'OK', 'OR', 'PA', 'PR', 'RI', 'SC', 'SD', 'TN', 'TX', 'UT', 'VA', 'VT', 'WA', 'WI', 'WV', 'WY' ]

# population data copied from http://worldpopulationreview.com/states and Wikipedia
population = {
  'AK' =>   738068,
  'AL' =>  4888949,
  'AR' =>     3020327,
  'AZ' =>  7123898,
  'CA' =>   39776830,
  'CO' =>     5684203,
  'CT' =>  3588683,
  'DC' => 703608,
  'DE' =>     971180,
  'FL' =>  21312211,
  'GA' =>  10545138,
  'HI' =>   1426393,
  'IA' =>     3160553,
  'ID' =>    1753860,
  'IL' =>     12768320,
  'IN' =>  6699629,
  'KS' =>   2918515,
  'KY' =>     4472265,
  'LA' =>    4682509,
  'MA' =>    6895917,
  'MD' =>     6079602,
  'ME' =>    1341582,
  'MI' =>     9991177,
  'MN' =>   5628162,
  'MO' =>    6135888,
  'MS' => 2982785,
  'MT' => 1062330,
  'NC' => 10390149,
  'ND' => 755238,
  'NE' =>    1932549,
  'NH' => 1350575,
  'NJ' => 9032872,
  'NM' => 2090708,
  'NV' =>  3056824,
  'NY' => 19862512,
  'OH' =>    11694664,
  'OK' => 3940521,
  'OR' =>  4199563,
  'PA' =>    12823989,
  'PR' =>    3411307,
  'RI' => 1061712,
  'SC' => 5088916,
  'SD' => 877790,
  'TN' => 6782564,
  'TX' => 28704330,
  'UT' =>    3159345,
  'VT' => 623960,
  'VA' =>    8525660,
  'WA' =>  7530552,
  'WV' => 1803077,
  'WI' =>   5818049,
  'WY' => 573720,
}

seats_held = Hash.new(0)
pvalue = Hash.new(0)

states.each do |state|
  pvalue[state] = population[state] * get_multiplier(1)
end

383.times do
  # what state has largest pvalue
  state = largest_hash_key(pvalue)
  # give seat to that state
  seats_held[state] += 1
  # update pvalue for that state
  pvalue[state] = population[state] * get_multiplier(seats_held[state])
end

# Start with 50 assigned
total = 52

states.each do |state|
  # Each state gets 1 seat by default
  puts "#{state} seats: " + (seats_held[state] + 1).to_s
  # Total seats
  total += seats_held[state]
end

puts "Total: #{total}"