SquareSum exercize for RubyReloaded

square_sum.rb

class MatrixNumericError < StandardError; end
class MatrixLengthError < StandardError; end
class MatrixSizeError < StandardError; end

class Sum
  attr_accessor :value, :location

  def to_s
    "#{value} starting at location #{location.join(', ')}"
  end

  def include? test_loc
    x_array = (location[0]..location[0] + 1).to_a
    y_array = (location[1]..location[1] + 1).to_a
    x_array.include?(test_loc[:x]) && y_array.include?(test_loc[:y])
  end

end

class SquareSum
  attr_reader :max, :min

  def initialize(matrix)
    @matrix = matrix
    @max = Sum.new
    @min = Sum.new

    validate_matrix
  end

  def calculate
    @matrix.each_with_index do |top_line, y_index|
      bottom_line = @matrix[y_index + 1]

      break unless bottom_line

      max_length = top_line.length - 1

      max_length.times do |x_index|

        arr_one = top_line[x_index..x_index+1]
        val_one = arr_one.inject(&:+)

        arr_two = bottom_line[x_index..x_index+1]
        val_two = arr_two.inject(&:+)

        this_sum = val_one + val_two

        if [email protected] || this_sum > @max.value
          @max.value = this_sum
          @max.location = [x_index, y_index]
        elsif [email protected] || this_sum < @min.value
          @min.value = this_sum
          @min.location = [x_index, y_index]
        end
      end
    end
  end

  def max_value
    @max.value
  end

  def min_value
    @min.value
  end

  def pretty_output
    y_axis = 0
    output = @matrix.map do |array|
      x_axis = 0

      result = array.map do |item|
        item_result = if @max.include?({ x: x_axis, y: y_axis })
          "\033[32m#{item}\033[0m"
        elsif @min.include?({ x: x_axis, y: y_axis })
          "\033[31m#{item}\033[0m"
        else
          item
        end
        x_axis += 1
        item_result
      end.join(" ")
      y_axis += 1
      result
    end
    output.unshift "\033[31mMin\033[0m"
    output.unshift "\033[32mMax\033[0m"
    output.unshift ""
    output.join("\n")
  end

  private

  def validate_matrix
    begin
      @matrix.flatten(1).inject(&:+)
    rescue TypeError
      raise MatrixNumericError, "Matrix must only contain numbers!"
    end

    unless @matrix.map(&:size).uniq.size == 1
      raise MatrixLengthError, "Matrix sub-arrays must all be of equal length!"
    end

    unless @matrix.size > 1 && @matrix.first.size > 1
      raise MatrixSizeError, "Must be at least 2 rows and 2 columns in the matrix"
    end
  end
end


if __FILE__ == $0
  arr = [ [1, 4, 6, 1, 9],
          [7, 7, 9, 3, 7],
          [3, 2, 4, 8, 3],
          [5, 5, 8, 5, 5],
          [2, 1, 4, 3, 1],
          [6, 0, 5, 7, 4],
          [6, 7, 0, 1, 3],
          [9, 4, 0, 4, 6],
          [1, 2, 6, 1, 0] ]


  sum = SquareSum.new arr
  sum.calculate
  puts ""
  puts "Max = #{sum.max}"
  puts "Min = #{sum.min}"

  puts sum.pretty_output
end

square_sum_spec.rb

require 'minitest/spec'
require 'minitest/autorun'

require_relative 'square_sum'

describe "Valid matrices" do

  before do
    arr = [ [1, 4, 6, 1, 9],
            [3, 7, 9, 2, 3],
            [9, 2, 0, 4, 6],
            [1, 2, 6, 1, 0] ]

    @sum = SquareSum.new arr
    @sum.calculate
  end

  it "can return the max value" do
    @sum.max_value.must_equal 26
  end

  it "can return the min value" do
    @sum.min_value.must_equal 10
  end

end

describe "Invalid matrices" do
  it "cannot contain non numeric values" do
    arr = [ [1, 4, "FooBar", 1, 9],
            [3, 7, 9, 2, 3] ]
    lambda { SquareSum.new(arr) }.must_raise MatrixNumericError
  end

  it "cannot contain other arrays" do
    arr = [ [1, 4, [1, 2, 3], 1, 9],
            [3, 7, 9, 2, 3] ]
    lambda { SquareSum.new(arr) }.must_raise MatrixNumericError
  end

  it "cannot contain nil values" do
    arr = [ [1, 4, nil, 1, 9],
            [3, 7, 9, 2, 3] ]
    lambda { SquareSum.new(arr) }.must_raise MatrixNumericError
  end

  it "has even rows" do
    arr = [ [1, 4, 3, 1, 9, 16],
            [3, 7, 9, 2, 3] ]
    lambda { SquareSum.new(arr) }.must_raise MatrixLengthError
  end

  it "has at least 2 rows" do
    arr = [[1, 2, 3, 4]]
    lambda { SquareSum.new(arr) }.must_raise MatrixSizeError
  end

  it "has at least 2 columns" do
    arr = [[1], [2], [3]]
    lambda { SquareSum.new(arr) }.must_raise MatrixSizeError
  end
end