Monte Carlo Dock Capacity Planning

boat.rb

#!/bin/ruby

BOAT_SIZES =  [19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30]
BOAT_COUNTS = [ 3,  3,  3,  4,  5,  6,  7,  5,  4,  4,  4,  4]

ALL_BOATS = BOAT_SIZES.zip(BOAT_COUNTS).map { |s,c| Array.new(c, s) }.flatten

BUFFER = 3  # Spacing between boats
MAX_SIZES = 23.upto(34) # Maximum length overall permitted to moore
ITERATIONS = 5000

MAX_DOCK_LENGTH = 316

MAX_SIZES.each do |max_size|
  total_boats_moored = []
  ITERATIONS.times do |i|
    arrivals = ALL_BOATS.shuffle
    remaining_capacity = MAX_DOCK_LENGTH
    boats_moored = 0
    next_arrival = arrivals.shift
    until remaining_capacity < (next_arrival + BUFFER) || arrivals.length == 0
      if next_arrival > max_size
        next_arrival = arrivals.shift
        next
      end
      boats_moored += 1
      remaining_capacity -= (next_arrival + BUFFER)
      next_arrival = arrivals.shift
    end
    total_boats_moored << boats_moored
  end
  histogram = total_boats_moored.group_by { |v| v }.transform_values { |v| v.size.to_f / ITERATIONS * 100 }.sort_by { |_, v| v }
  average = total_boats_moored.sum.to_f / total_boats_moored.count
  puts "#{max_size} offers #{histogram} (average #{average})"
end