Cookpad Code Puzzle for RubyKaigi 2022 solutions

cookpad-puzzles-2022.rb

# https://ruby-puzzles-2022.cookpad.tech/


def answer1(n)
  n+1
end


def answer2(str)
  str.upcase
end


def answer3(n)
  (0..n).to_a
end


def answer4
  yield + 42
end


def answer5(n, m=1)
  n+m
end


def answer6(n)
  (n-1).remainder(9)+1
end


def answer7(n)
  # $stderr.puts n.inspect
  JS.eval("console.log('#{n}')")
  n.succ
end


def answer8(n)
  n.to_s(2).count("1")
end


class M
  def method_missing(name, *args)
    puts "#{name}(" + args.map{_1.inspect}*',' + ")"
  end
end

p func9(M.new)

def answer9(s)
  s.gsub("u-g0t-me", "yikes")
end


$n=func10
def answer10(a=nil)
  if a
    $n=0
  else
    $n+=1
  end
end


def answer11(v)
  v.hash
end


def answer12(v)
  v.to_s.chars.sort.chunk{_1}.map{_2.length}.inject(:*)
end


def answer13(i)
  e = Encoding.list[i]
  e && e.name[0..1]
end


def answer14(i)
  if i < 0
    "M"
  elsif i < 20
    "ZOTTFFSSENTETTFFSSEN"[i]
  elsif i < 100
    answer14(i/10)
  elsif i < 1000
    answer14(i/100)
  elsif i == 1000
    "T" # !?  "O"ne thousandでは?
  else
    answer14(i/1000)
  end
end


def answer15(i)
  c = Object.constants.map{_1.to_s}.sort[i]
  c && c[0..1]
end


p func16{|&a| p a}
p func16{|&a| p a[]}

def answer16(&blk)
  called = false
  blk.call{
    called = true
  }
  called
end


def answer17(t)
  JS.eval("alert('#{t}')")
end


def answer18(s)
  s.split(/(\D)/).filter{|tk|tk!=""}.map{|tk|
    if tk =~ /[0-9]+/
      tk.to_i
    else
      tk
    end
  }
end


def parse_expr(tokens)
  e = parse_product(tokens)
  while !tokens.empty?
    case tokens[0]
    when "+", "-"
      op = tokens.shift
      e = [op, e, parse_product(tokens)]
    when ")"
      break
    else
      raise Exception.new("parse error at #{tokens} : current e = #{e}")
    end
  end
  e
end

def parse_product(tokens)
  e = parse_value(tokens)
  while !tokens.empty?
    case tokens[0]
    when "*", "/"
      op = tokens.shift
      e = [op, e, parse_value(tokens)]
    else
      break
    end
  end
  e
end

def parse_value(tokens)
  if tokens[0] == "("
    tokens.shift
    e = parse_expr(tokens)
    if tokens[0] == ")"
      tokens.shift
      return e
    else
      raise Exception.new("')' not found")
    end
  elsif tokens[0].is_a?(Numeric)
    ["value", tokens.shift]
  else
    raise Exception.new("parse error at #{tokens}")
  end
end

def answer19(tokens)
  d = tokens.dup
  parsed = parse_expr(d)
  if !d.empty?
    raise Exception.new("parse error at #{d} / parsed: #{parsed}")
  end
  parsed
end


def answer20(ast)
  op = ast[0]
  if op == "value"
    ast[1]
  else
    l = answer20(ast[1])
    r = answer20(ast[2])
    case op
    when "+" then l+r
    when "-" then l-r
    when "*" then l*r
    when "/" then l/r
    else
      raise Exception.new("unknown operator: #{op}")
    end
  end
end