Ruby programs are executed on the server with the Ruby 1.9.3. The syntax is checked with command: ruby -c %1. Interpreter is invoked without parameters: ruby %1.

You can find the interpreter here.

An example of solving a problem

A sample solution for the 1000. A + B problem in Ruby:

a, b = gets.split(" ").map {|x| x.to_i}
puts (a + b)

A sample solution for the 1001. Reverse Root in Ruby:

tokens = []
while string = gets do
   string.split().each do |token|
      tokens << token
   end
end
tokens.reverse.each do |token|
   puts (token.to_i ** 0.5).round(4) 
end