drdrang (Leancrew.com) counting-heads done in ruby

gistfile1.rb

#!/usr/bin/env ruby

# See http://leancrew.com/all-this/2015/02/counting-heads/
#
# Eight people are sitting around a circular table. Each has a coin. They all
# flip their coins. What is the probability that no two adjacent people will
# get heads?

rounds = []
(0..255).each { |i|
   num = i.to_s(2).rjust(8, '0')
   if num.include?('11') or (num.start_with?('1') and num.end_with?('1'))
     rounds << num
   end
}

puts "Total Rounds with adjacent Heads #{rounds.size}"
puts "Total Rounds with no adjacent Heads #{256 - rounds.size}"
puts "Probablity that no adjacent Heads is #{(256 - rounds.size)/256.0}"