「オフラインリアルタイムどう書く第17回(折って切る)」の問題を解いてみた

横浜へなちょこプログラミング勉強会にて過去に出題された折って切るを解いてみた。
回答にかかった時間は60分を少しオーバー。

class OrigamiFold
  def initialize input
    order, @cut = input.split "-"
    @order = order.chars
    @origami = Origami.new
  end

  def exec
    @order.each{|o| @origami.fold o}
    @origami.cut @cut
  end
end

class Origami
  def initialize
    @count = 1
    @layer = {t: 0, b: 0, l: 0, r: 0}
  end

  def fold order
    case order.to_sym
    when :T then @layer[:t], @layer[:b] = calc_layer(@layer[:t], @layer[:b])
    when :B then @layer[:b], @layer[:t] = calc_layer(@layer[:t], @layer[:b])
    when :L then @layer[:l], @layer[:r] = calc_layer(@layer[:l], @layer[:r])
    when :R then @layer[:r], @layer[:l] = calc_layer(@layer[:l], @layer[:r])
    end
  end

  def cut corner
    corner.chars.map{|c| @layer[c.to_sym]}.inject(1, &:*)
  end

  private

  def calc_layer f1, f2
    [f1 + f2 + 1, f1 + f2]
  end
end

test = <<_TEST
/*0*/ test( "RRTRB-bl", "6" );    
/*1*/ test( "R-tr", "0" );    
/*2*/ test( "L-br", "0" );    
/*3*/ test( "T-tl", "0" );    
/*4*/ test( "B-tl", "0" );    
/*5*/ test( "BL-br", "0" );    
/*6*/ test( "LB-tl", "0" );    
/*7*/ test( "RL-tl", "0" );    
/*8*/ test( "BL-tl", "0" );    
/*9*/ test( "TL-bl", "0" );    
/*10*/ test( "RT-tr", "1" );    
/*11*/ test( "TRB-tl", "0" );    
/*12*/ test( "TRL-bl", "0" );    
/*13*/ test( "TRB-br", "2" );    
/*14*/ test( "LLB-bl", "2" );    
/*15*/ test( "RTL-tr", "1" );    
/*16*/ test( "LBB-tr", "0" );    
/*17*/ test( "TLL-tl", "2" );    
/*18*/ test( "RLRR-tr", "0" );    
/*19*/ test( "BBTL-tl", "4" );    
/*20*/ test( "TBBT-tr", "0" );    
/*21*/ test( "LLBR-tl", "0" );    
/*22*/ test( "LBRT-tl", "2" );    
/*23*/ test( "RLBL-bl", "4" );    
/*24*/ test( "BRRL-br", "3" );    
/*25*/ test( "TBBTL-tl", "8" );    
/*26*/ test( "TLBBT-br", "0" );    
/*27*/ test( "LRBLL-br", "7" );    
/*28*/ test( "TRRTT-br", "6" );    
/*29*/ test( "BBBLB-br", "0" );    
/*30*/ test( "RTTTR-tl", "4" );    
/*31*/ test( "BBLLL-br", "6" );    
/*32*/ test( "RRLLTR-tr", "16" );    
/*33*/ test( "TTRBLB-br", "8" );    
/*34*/ test( "LRBRBR-bl", "14" );    
/*35*/ test( "RBBLRL-tl", "8" );    
/*36*/ test( "RTRLTB-tl", "12" );    
/*37*/ test( "LBLRTR-tl", "14" );    
/*38*/ test( "RRLTRL-tl", "16" );    
/*39*/ test( "TBLTRR-br", "12" );    
/*40*/ test( "TTTRLTT-bl", "30" );    
/*41*/ test( "TBBRTBL-tr", "15" );    
/*42*/ test( "TRTRTLL-tr", "28" );    
/*43*/ test( "TLLRTRB-tr", "24" );    
/*44*/ test( "RLLBRLB-tr", "15" );    
/*45*/ test( "LTLRRBT-tr", "32" );    
/*46*/ test( "RBBRBLT-br", "21" );    
/*47*/ test( "LLRLRLR-tr", "0" );
_TEST

require 'minitest/autorun'

describe 'FoldCut' do
  test.split("\n").each do |line|
    t, n, input, expect = line.match(/^\/\*(\d+)\*\/\s*test\(\s*"([^"]+)",\s*"([^"]+)"\s*\);\s*$/).to_a
    of = OrigamiFold.new input
    it input do
      assert_equal expect, of.exec.to_s
    end
  end
end