namespace ProjectEuler
open ProjectEuler.Core

module Euler4 =

  // Project Euler #4
  // Correct answer: 906609

  let runner =

    let sum = [for x in [100..999] do
                for y in [100..999] do yield x * y]
                |> Seq.filter(fun z -> z = int32(new string(Array.rev (z.ToString().ToCharArray()))))
                |> Seq.max

    printeul 4 sum