「オフラインリアルタイムどう書く第24回(多段階選抜)」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多段階選抜を解いてみた。
回答にかかった時間は30分程度。

本当は@listは長さ決め打ちではなく1..Float::INFINITYにしたかったのだが、Enumerator::Lazyでは解けそうになかったので1..2000という範囲でやりくりすることにした。
今回のテストケースを満たせばよいという考え方はやはり性に合わないのだが、これ以外回答が思いつかなかったのが悔やまれる。

class Selection
  def seq input
    @list = (1..2000).to_a
    input.chars.each{|c|
      case c
      when "2".."9"
        delete_multiple c.to_i
      when "S"
        delete_indexes square_next
      when "s"
        delete_indexes square_prev
      when "C"
        delete_indexes cubic_next
      when "c"
        delete_indexes cubic_prev
      when "h"
        @list = @list.drop(100)
      end
    }
    @list[0..9]
  end

  private
  def delete_multiple n
    @list = @list.reject.with_index(1){|_, i|
      (i % n) === 0
    }
  end

  def delete_indexes indexes
    indexes.reverse.map{|i|
      @list.delete_at i
    }
  end

  def square_next
    next_indexes square.map{|n| @list.index(n)}
  end

  def square_prev
    prev_indexes square.map{|n| @list.index(n)}
  end

  def cubic_next
    next_indexes cubic.map{|n| @list.index(n)}
  end

  def cubic_prev
    prev_indexes cubic.map{|n| @list.index(n)}
  end

  def next_indexes indexes
    indexes.map{|i| i + 1}.reject{|i| i < 0 || @list.size <= i}
  end

  def prev_indexes indexes
    indexes.map{|i| i - 1}.reject{|i| i < 0 || @list.size <= i}
  end

  def square
    @list.select{|n|
      sq = Math.sqrt n
      sq.to_i === sq
    }
  end

  def cubic
    @list.select{|n|
      cu = Math.cbrt n
      cu.to_i === cu
    }
  end
end

test = <<_TEST
/*0*/ test( "ss6cc24S", "1,9,21,30,33,37,42,44,49,56" );    
/*1*/ test( "h", "101,102,103,104,105,106,107,108,109,110" );    
/*2*/ test( "hh", "201,202,203,204,205,206,207,208,209,210" );    
/*3*/ test( "hhh", "301,302,303,304,305,306,307,308,309,310" );    
/*4*/ test( "2", "1,3,5,7,9,11,13,15,17,19" );    
/*5*/ test( "22", "1,5,9,13,17,21,25,29,33,37" );    
/*6*/ test( "222", "1,9,17,25,33,41,49,57,65,73" );    
/*7*/ test( "3", "1,2,4,5,7,8,10,11,13,14" );    
/*8*/ test( "33", "1,2,5,7,10,11,14,16,19,20" );    
/*9*/ test( "333", "1,2,7,10,14,16,20,23,28,29" );    
/*10*/ test( "s", "1,2,4,5,6,7,9,10,11,12" );    
/*11*/ test( "ss", "1,4,5,6,9,10,11,12,13,16" );    
/*12*/ test( "sss", "4,5,9,10,11,12,16,17,18,19" );    
/*13*/ test( "S", "1,3,4,6,7,8,9,11,12,13" );    
/*14*/ test( "SS", "1,4,7,8,9,12,13,14,15,16" );    
/*15*/ test( "SSS", "1,8,9,13,14,15,16,20,21,22" );    
/*16*/ test( "c", "1,2,3,4,5,6,8,9,10,11" );    
/*17*/ test( "cc", "1,2,3,4,5,8,9,10,11,12" );    
/*18*/ test( "ccc", "1,2,3,4,8,9,10,11,12,13" );    
/*19*/ test( "C", "1,3,4,5,6,7,8,10,11,12" );    
/*20*/ test( "CC", "1,4,5,6,7,8,11,12,13,14" );    
/*21*/ test( "CCC", "1,5,6,7,8,12,13,14,15,16" );    
/*22*/ test( "23", "1,3,7,9,13,15,19,21,25,27" );    
/*23*/ test( "32", "1,4,7,10,13,16,19,22,25,28" );    
/*24*/ test( "2h", "201,203,205,207,209,211,213,215,217,219" );    
/*25*/ test( "h2", "101,103,105,107,109,111,113,115,117,119" );    
/*26*/ test( "sC", "1,4,5,6,7,9,10,11,12,13" );    
/*27*/ test( "Cs", "1,4,5,6,7,8,10,11,12,13" );    
/*28*/ test( "s468", "1,2,4,6,7,11,12,16,17,20" );    
/*29*/ test( "S468", "1,3,4,7,8,12,13,16,18,21" );    
/*30*/ test( "cc579", "1,2,3,4,8,9,11,13,15,16" );    
/*31*/ test( "CC579", "1,4,5,6,8,11,13,15,17,18" );    
/*32*/ test( "85", "1,2,3,4,6,7,9,10,12,13" );    
/*33*/ test( "sh", "110,111,112,113,114,115,116,117,118,119" );    
/*34*/ test( "94h", "150,151,154,155,156,158,159,160,163,164" );    
/*35*/ test( "h9c8", "101,102,103,104,105,106,107,110,111,112" );    
/*36*/ test( "Cc3s", "1,3,5,6,10,11,13,16,17,19" );    
/*37*/ test( "cs4h6", "149,150,152,153,154,157,158,160,161,162" );    
/*38*/ test( "84523c", "1,3,11,15,23,26,34,38,46,49" );    
/*39*/ test( "54C78hS", "228,231,232,233,236,241,242,243,246,247" );    
/*40*/ test( "65h7ccs", "151,152,153,154,157,158,160,163,164,165" );    
/*41*/ test( "c95hSc2C", "145,147,151,153,156,159,162,164,168,171" );    
/*42*/ test( "c5h3Ss794", "130,131,133,137,138,142,148,150,152,157" );    
/*43*/ test( "7ShscC846", "129,130,131,134,135,139,141,142,146,148" );    
/*44*/ test( "cshSCCS7ch", "253,254,256,259,260,261,263,264,265,266" );    
/*45*/ test( "hhC7849Ss6C", "201,202,203,205,206,211,212,216,220,225" );    
/*46*/ test( "hhsc3C987Ccs", "201,202,204,205,207,208,214,217,218,220" );    
/*47*/ test( "SC7S8hc59ss2", "162,169,174,178,182,185,188,194,199,203" );    
/*48*/ test( "s7S6c35C9CShc", "367,371,377,379,380,385,387,388,392,395" );    
/*49*/ test( "4scC3hh982Cc5s", "422,426,430,434,447,451,459,463,471,479" );    
/*50*/ test( "23h465Ssc9CchC", "1027,1033,1045,1047,1057,1069,1071,1075,1081,1093" );
_TEST

require 'minitest/autorun'

describe 'Selection' do
  selection = Selection.new
  test.split("\n").each do |line|
    t, n, input, expect = line.match(/^\/\*(\d+)\*\/\s*test\(\s*"([^"]+)",\s*"([^"]+)"\s*\);*\s*$/).to_a
    it input do
      assert_equal expect, selection.seq(input).join(",")
    end
  end
end