#!/usr/bin/env ruby
Dan M. - http://www.dcmanges.com
Ruby Q. #124 - Ruby Quiz - Magic Squares (#124)
module ArrayExtension
def sum
inject { |x,y| x + y } || 0
end
end
Array.send :include, ArrayExtension
class MagicSquare
def initialize(size)
@size = size
end
def row
result
end
def column
row[0].zip(*row[1…-1])
end
def diagonal
first_diagonal = (0…@size).map { |index| row[index][index] }
second_diagonal = (0…@size).map { |index|
row[index][@size-index-1] }
[first_diagonal, second_diagonal]
end
protected
def result
@result ||= MagicSquareGenerator.new(@size).generate
end
def method_missing(method, *args, &block)
result.send(method, *args, &block)
end
end
class MagicSquareGenerator
def initialize(size)
@size = size
end
def generate
square = (0…@size).map { [nil] * @size }
x, y = 0, @size / 2
1.upto(@size**2) do |current|
x, y = add(x,2), add(y,1) if square[x][y]
square[x][y] = current
x, y = add(x, -1), add(y, -1)
end
square
end
private
def add(x,y)
value = x + y
value = @size + value if value < 0
value = value % @size if value >= @size
value
end
end
class MagicSquareFormatter
def initialize(magic_square)
@magic_square = magic_square
end
def formatted_square
formatting = “|” + " %#{number_width}s |" * size
rows = @magic_square.map { |row| formatting % row }
body = rows.join(“\n#{row_break}\n”)
“#{row_break}\n#{body}\n#{row_break}”
end
private
def row_break
dashes = ‘-’ * (row_width-2)
‘+’ + dashes + ‘+’
end
def number_width
(@magic_square.size**2).to_s.length
end
def row_width
(number_width+3) * size + 1
end
def size
@magic_square.size
end
end
if ARGV.first =~ /^\d+$/
size = ARGV.first.to_i
puts “Generating #{size}x#{size} magic square…”
magic_square = MagicSquare.new(size)
puts MagicSquareFormatter.new(magic_square).formatted_square
elsif FILE == $0
require ‘test/unit’
class MagicSquare3x3Test < Test::Unit::TestCase
def setup
@magic_square = MagicSquare.new(3)
end
def test_sum_of_rows_columns_and_diagonals
(0...3).each do |index|
assert_equal 15, @magic_square.row[index].sum
assert_equal 15, @magic_square.column[index].sum
end
assert_equal 15, @magic_square.diagonal[0].sum
assert_equal 15, @magic_square.diagonal[1].sum
end
def test_expected_values
assert_equal [1,2,3,4,5,6,7,8,9], @magic_square.flatten.sort
end
end
class MagicSquare9x9Test < Test::Unit::TestCase
def setup
@magic_square = MagicSquare.new(9)
end
def test_sum_of_rows_columns_and_diagonals
(0...9).each do |index|
assert_equal 369, @magic_square.row[index].sum
assert_equal 369, @magic_square.column[index].sum
end
assert_equal 369, @magic_square.diagonal[0].sum
assert_equal 369, @magic_square.diagonal[1].sum
end
def test_expected_values
assert_equal (1..81).to_a, @magic_square.flatten.sort
end
end
end
END
$ ruby rubyquiz124.rb 9
Generating 9x9 magic square…
±-------------------------------------------+
| 45 | 34 | 23 | 12 | 1 | 80 | 69 | 58 | 47 |
±-------------------------------------------+
| 46 | 44 | 33 | 22 | 11 | 9 | 79 | 68 | 57 |
±-------------------------------------------+
| 56 | 54 | 43 | 32 | 21 | 10 | 8 | 78 | 67 |
±-------------------------------------------+
| 66 | 55 | 53 | 42 | 31 | 20 | 18 | 7 | 77 |
±-------------------------------------------+
| 76 | 65 | 63 | 52 | 41 | 30 | 19 | 17 | 6 |
±-------------------------------------------+
| 5 | 75 | 64 | 62 | 51 | 40 | 29 | 27 | 16 |
±-------------------------------------------+
| 15 | 4 | 74 | 72 | 61 | 50 | 39 | 28 | 26 |
±-------------------------------------------+
| 25 | 14 | 3 | 73 | 71 | 60 | 49 | 38 | 36 |
±-------------------------------------------+
| 35 | 24 | 13 | 2 | 81 | 70 | 59 | 48 | 37 |
±-------------------------------------------+
