Here's a Ruby implementation of a bomb-free space optima number
calculator. It's also available (with versions in C and Python) on the
Optima number page:

* https://corewar.co.uk/optima.htm

# rubyoptima v0.1 - Core War optima number calculator in Ruby by John
Metcalf
# using the bomb-free space method
# Usage: $ irb -r ./optima.rb
# >> optima(coresize, modulo)

def optima(coresize, modulo = 1)
scores = []
(modulo..coresize / 2).step(modulo) do |step|
if coresize.gcd(step) == modulo
score = coresize - 1
high = low = pos = step
until pos.zero?
pos = (pos + step) % coresize
high = [pos, high].max
low = [pos, low].min
score += coresize - high + low - 1
end
scores << [score, step]
end
end
puts 'step,score'
scores.sort.take(20).each { |i| puts i.reverse.join(',') }
nil
end

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