test_array_intersection_and_union.rb

require 'benchmark'

module Config
  N = 50000
  A_LENGTH = 100
  B_LENGTH = 10

  def self.generate_array(length)
    (1..length).map { (rand * length).round }
  end
end

def compare(a, b, &block)
  a_then_b = Benchmark.realtime { Config::N.times { block.call(a, b) } }
  b_then_a = Benchmark.realtime { Config::N.times { block.call(b, a) } }

  ((b_then_a - a_then_b) / b_then_a) * 100
end

puts "A is an array of #{Config::A_LENGTH} elements, B - #{Config::B_LENGTH} elements"

5.times {
  a = Config.generate_array(Config::A_LENGTH)
  b = Config.generate_array(Config::B_LENGTH)

  percent = compare(a, b) { |a, b| a | b }

  puts "(A | B) is #{percent.round}% faster then (B | A)"
}

5.times {
  a = Config.generate_array(Config::A_LENGTH)
  b = Config.generate_array(Config::B_LENGTH)

  percent = compare(a, b) { |a, b| a & b }

  puts "(A & B) is #{percent.round}% faster then (B & A)"
}