Project Euler Problem #11

p11.rb

#!/usr/bin/env ruby

input = ARGV[0]


class Grid
  attr_reader :data

  def initialize file, count=4
    @data = IO.read(file).lines.map{|l| l.split " "}.map{|l| l.map{|i| i.to_i}}
    @count = count
  end

  def maximum_product g
    g.map do |line|
      line.each_cons(@count).map do |arr|
        arr.inject(1, :*)
      end
    end.flatten.max
  end

  def horizontal
    maximum_product data
  end

  def vertical
    maximum_product data.transpose
  end

  def right_diagonal
    maximum_product data.each_with_index.map{|e,i| e.rotate(i)}.transpose
  end

  def left_diagonal
    maximum_product data.each_with_index.map{|e, i| e.rotate(-i)}.transpose
  end

  def result
    [ vertical, horizontal, left_diagonal, right_diagonal ].max
  end
end


puts Grid.new(input).result