best-wing-prices.rb

#!/usr/bin/env ruby

require "ruby-cbc"
require "csv"

wings = {
  4   => 4.55,
  5   => 5.70,
  6   => 6.80,
  7   => 7.95,
  8   => 9.10,
  9   => 10.20,
  10  => 11.35,
  11  => 12.50,
  12  => 13.60,
  13  => 14.75,
  14  => 15.90,
  15  => 17.00,
  16  => 18.15,
  17  => 19.30,
  18  => 20.40,
  19  => 21.55,
  20  => 22.70,
  21  => 23.80,
  22  => 24.95,
  23  => 26.10,
  24  => 27.25,
  25  => 27.80,
  26  => 28.95,
  27  => 30.10,
  28  => 31.20,
  29  => 32.35,
  30  => 33.50,
  35  => 39.15,
  40  => 44.80,
  45  => 50.50,
  50  => 55.60,
  60  => 67.00,
  70  => 78.30,
  75  => 83.45,
  80  => 89.10,
  90  => 100.45,
  100 => 111.25,
  125 => 139.00,
  150 => 166.85,
  200 => 222.50
}

CSV.open("best_combo.csv", "w") do |csv|
  csv << ["wings", "price"]
  best_combos = (wings.keys.min .. wings.keys.max).each do |x|
    m = Cbc::Model.new
    vars = Array.new(wings.size)
    vars = m.int_var_array(wings.size, 0..Cbc::INF)
    vars = vars.each_with_index.map do |var,i|
      {
        var: var,
        num_wings: Array(wings)[i][0],
        price: Array(wings)[i][1]
      }
    end
    m.minimize(vars.map{|x| x[:price] * x[:var]}.reduce(:+))
    m.enforce(vars.map{|x| x[:num_wings] * x[:var]}.reduce(:+) == x)
    p = m.to_problem
    p.solve
    if p.proven_infeasible?
      csv << [x, nil]
    else
      csv << [x, vars.map{|x| p.value_of(x[:var]) * x[:price]}.reduce(:+)]
    end
  end
end