Project Euler problem 9. Using formula.

euler_9.rb

require 'benchmark'
result = []
Benchmark.bm(7) do |reports|
  reports.report do
    (2..500).each do |x|
      (2..500).each do |y|
        next unless x > y
        a = [x*x-y*y, 2*x*y, x*x+y*y]
        next unless (a[0] + a[1] + a[2] === 1000)
        next unless (a[0]*a[0]+a[1]*a[1] === a[2]*a[2])
        result << a
        puts a
      end
    end
  end
end


__END__

    user   system    total        real
0.110000 0.000000 0.110000 (0.10.7985)

The formula used is Euler's formula for finding Pythagorean triplets.