An implementation of Euclid's algorithm in Ruby finding the highest common factor for two numbers.

euclids.rb

def euclids(a, b) # Euclid's Algorithm
  quotient = a / b
  remainder = a % b # modulo
  puts "#{a} = #{quotient}(#{b}) + #{remainder} [hcf(#{a}, #{b})]"
  return b if remainder.zero?
  euclids(b, remainder)
end

def hcf(a, b)
  euclids(a, b)
end

begin
  num1 = ARGV[0].chomp.to_i
  num2 = ARGV[1].chomp.to_i
  puts "\nhcf(#{num1}, #{num2}) = #{hcf(num1, num2)}"
rescue
  puts "Invalid arguments given!"
  puts "euclids.rb <num1> <num2>"
end