Rubyで簡易oxゲーム

oxgame.rb

$ary = (1...10).to_a
$player = -1
$cnt = 1

def showDisp
  puts "Select number between 1...9"
  (0...9).each do |i|
    if (i + 1) % 3 == 0 then
      puts getStone($ary[i])
    else
      print getStone($ary[i])
    end
  end
end

def getStone(n)
  if n == 12
    return "o"
  elsif n == 10
    return "x"
  end
  return n
end

def setStone(p, n)
  if getStone($ary[n]).class == Fixnum && n >= 0 then
    $ary[n] = 11 + p
    $cnt += 1
  else
    puts "error"
    $player *= -1
  end
end

def checkComp
  if $ary[0] == $ary[1] && $ary[1] == $ary[2] then return true end
  if $ary[3] == $ary[4] && $ary[4] == $ary[5] then return true end
  if $ary[6] == $ary[7] && $ary[7] == $ary[8] then return true end
  if $ary[0] == $ary[3] && $ary[3] == $ary[6] then return true end
  if $ary[1] == $ary[4] && $ary[4] == $ary[7] then return true end
  if $ary[2] == $ary[5] && $ary[5] == $ary[8] then return true end
  if $ary[0] == $ary[4] && $ary[4] == $ary[8] then return true end
  if $ary[6] == $ary[4] && $ary[4] == $ary[2] then return true end
  return false
end

system("cls")
showDisp
while (s = gets) != "q\n"
  setStone($player *= -1, s.to_i - 1)
  system("cls")
  showDisp
  if checkComp then
    print "Winner Player \"", getStone(11 + $player), "\"\n"
    exit
  end
  if $cnt > 9 then
    break
  end
end
puts "drow."