calculation.rb

#!/bin/env ruby
# -*- coding: utf-8 -*-

class MatrixCalc
  def initialize(matrix)
    @matrix = matrix
  end

  def input
    @input ||= traverse
  end

  def sum(index)
    input.take(index).reduce(:+)
  end

  def at(index)
    input[index - 1]
  end

  def traverse
    result = []
    x1, y1, x2, y2 = 0, 0, @matrix[0].size - 1, @matrix.size - 1

    matrix_iter = lambda do |direction|
      w = x2 - x1 + 1
      h = y2 - y1 + 1

      if w <= 0 or h <= 0
        return
      end

      if direction == 0
        result += (x1..x2).map { |x| @matrix[y1][x] }
        y1 += 1
      elsif direction == 1
        result += (y1..y2).map { |y| @matrix[y][x2] }
        x2 -= 1
      elsif direction == 2
        result += x2.downto(x1).map { |x| @matrix[y2][x] }
        y2 -= 1
      elsif direction == 3
        result += y2.downto(y1).map { |y| @matrix[y][x1] }
        x1 += 1
      end

      matrix_iter.call (direction + 1) % 4
    end
    matrix_iter.call 0
    result
  end
end

calculation_test.rb

#!/bin/env ruby
# -*- coding: utf-8 -*-

require 'test/unit'
require_relative 'calculation'

class CalculationTest < Test::Unit::TestCase
  def setup
    input = [ [12, 32, 9], [19, 5, 11], [43, 7, 34] ]
    @matrix = MatrixCalc.new(input)
  end

  def test_sum_three
    assert_equal 53, @matrix.sum(3)
  end

  def test_sum_eight
    assert_equal 167, @matrix.sum(8)
  end

  def test_position_three
    assert_equal 9, @matrix.at(3)
  end

  def test_position_seven
    assert_equal 43, @matrix.at(7)
  end

  # def test_visited
  #   assert_equal false, @matrix.visited?(3, 3)
  # end
end

class TraverseTest < Test::Unit::TestCase
  def test_with_2x2
    input = [ [12, 32], [7, 34] ]
    @matrix = MatrixCalc.new(input)
    assert_equal [12, 32, 34, 7], @matrix.traverse
  end

  def test_with_3x3
    input = [ [12, 17, 9], [19, 28, 11], [43, 7, 34] ]
    @matrix = MatrixCalc.new(input)
    assert_equal [12, 17, 9, 11, 34, 7, 43, 19, 28], @matrix.traverse
  end

  def test_with_4x4
# 12 32 09 11
# 08 54 76 23
# 27 18 25 09
# 11 23 78 63
    input = [ [12, 32, 9, 11], [8, 54, 76, 23], [27, 18, 25, 9], [11, 23, 78, 63] ]
    @matrix = MatrixCalc.new(input)
    assert_equal [12, 32, 9, 11, 23, 9, 63, 78, 23, 11, 27, 8, 54, 76, 25, 18], @matrix.traverse
  end

  def test_with_5x5
# 12 32 09 11 34
# 08 54 76 23 07
# 27 18 25 09 43
# 11 23 78 63 19
# 09 22 56 31 05
    input = [ [12, 32, 9, 11, 34], [8, 54, 76, 23, 7], [27, 18, 25, 9, 43], [11, 23, 78, 63, 19], [9, 22, 56, 31, 5] ]
    @matrix = MatrixCalc.new(input)
    assert_equal [12, 32, 9, 11, 34, 7, 43, 19, 5, 31, 56, 22, 9, 11, 27, 8, 54, 76, 23, 9, 63, 78, 23, 18, 25], @matrix.traverse
  end

  def test_with_3x2
# 12 17
#  9 11
# 19 28
    input = [ [12, 17], [9, 11], [19, 28] ]
    @matrix = MatrixCalc.new(input)
    assert_equal [12, 17, 11, 28, 19, 9], @matrix.traverse
  end

def test_with_4x6
# 12 17  9  7 21 10
# 19 28 11 25  2  6
# 10  3  8 13  4  29
# 5  12  9 14  31 18
    input = [ [12, 17, 9, 7, 21, 10], [19, 28, 11, 25, 2, 6], [10, 3, 8, 13, 4, 29], [5, 12, 9, 14, 31, 18]]
    @matrix = MatrixCalc.new(input)
    assert_equal [12, 17, 9, 7, 21, 10, 6, 29, 18, 31, 14, 9, 12, 5, 10, 19, 28, 11, 25, 2, 4, 13, 8, 3], @matrix.traverse
  end
end