https://marginalia.hatenablog.com/entry/2025/01/25/002512

A

Object.alias_method(:■, :method)

def gets(io) = io.gets.chomp
def split(s) = s.split("x").map(&:to_i)
def mul(ary) = ary[0] * ary[1]
def output(e) = STDOUT.puts e

(■(:gets) >> ■(:split) >> ■(:mul) >> ■(:output)).(STDIN)

B

Object.alias_method(:■, :method)

def gets(io) = io.gets.to_i
def output(e) = (STDOUT.puts e; exit)
def main(x)
  (2..).each do |n|
    if x == n
      output(n)
    else
      x /= n
    end
  end
end

(■(:gets) >> ■(:main)).(STDIN)

C

Object.alias_method(:■, :method)

def gets(io) = (io.gets; io.readlines(chomp: true))
def output(e) = STDOUT.puts e

def main(query)
  sum = [0]
  query.each do |q|
    tmp = q.split.map(&:to_i)
    case tmp[0]
    when 1
      sum << sum[-1] + tmp[1]
    when 2
      sum.shift
    else
      output(sum[tmp[1] - 1] - sum[0])
    end
  end
end

(■(:gets) >> ■(:main)).(STDIN)

D

Object.alias_method(:■, :method)

def gets(io) = io.gets.to_i
def output(e) = STDOUT.puts e
def amount_of_square(x) = (x - 1/2r) * 2 + 1
def in?(x, y, r) = Math.hypot(x, y) <= r

def x_reduce(x, y, r)
  x -= 1 until in?(x, y, r)
  x
end

def walk(r)
  x, y = r - 1/2r, 1/2r
  sum = amount_of_square(x)
  loop do
    y += 1
    if y >= r
      return sum.to_i
    else
      x = x_reduce(x, y, r)
      sum += amount_of_square(x) * 2
    end
  end
end

(■(:gets) >> ■(:walk) >> ■(:output)).(STDIN)