#!/usr/bin/env ruby

require 'benchmark'

class Integer

  def ackermann(n)

    return n + 1 if self == 0

    if n == 0

      (self - 1).ackermann(1)

    else

      (self - 1).ackermann(ackermann(n - 1))

    end

  end

end

results = Benchmark.bmbm do |bm|

  raise "Expecting one arg - second ackermann param" if ARGV.size == 0

  n = ARGV[0].to_i

  bm.report { 10.times { 3.ackermann(n) } }

end

puts "EXECUTION TIME: #{results[0].real * 1000.0}"