Find the greatest product of five consecutive digits in the 1000-digit number.

euler8.rb

# Find the greatest product of five consecutive digits in the 1000-digit number.

madness=7316717653133062491922511967442657474235534919493496983520312774506326239578318016984801869478851843858615607891129494954595017379583319528532088055111254069874715852386305071569329096329522744304355766896648950445244523161731856403098711121722383113622298934233803081353362766142828064444866452387493035890729629049156044077239071381051585930796086670172427121883998797908792274921901699720888093776657273330010533678812202354218097512545405947522435258490771167055601360483958644670632441572215539753697817977846174064955149290862569321978468622482839722413756570560574902614079729686524145351004748216637048440319989000889524345065854122758866688116427171479924442928230863465674813919123162824586178664583591245665294765456828489128831426076900422421902267105562632111110937054421750694165896040807198403850962455444362981230987879927244284909188845801561660979191338754992005240636899125607176060588611646710940507754100225698315520005593572972571636269561882670428252483600823257530420752963450

insanity = []

lunacy = madness.to_s.split("").map(&:to_i)

# puts lunacy.join(', ')

0.upto(lunacy.length - 5).map do |x|
  insanity << [lunacy[x], lunacy[x + 1], lunacy[x + 2],
                       lunacy[x + 3], lunacy[x + 4]]
end

puts "\n\nlunacy[0] is #{lunacy[0]}."


psycho = []
insanity.map { |five|
  psycho << { product: five.inject(:*),
              array: five }
}

puts "psycho[0] is #{psycho[0]}."

puts psycho.sort_by { |hash| hash[:product]}.last, "\n\n"