2つのバケツ

bucket_problem1.rb

#http://obelisk.hatenablog.com/entry/2017/12/01/041951
#B1リットル: 空(0), 入れる(1), B1→B2に移す(2)
#B2リットル: 空(3), 入れる(4), B2→B1に移す(5)

B1, B2 = 8, 5
TO = 1

def move(mass, f, t)
  if (a = mass - t) >= f
    t += f
    f = 0
  else
    t = mass
    f -= a
  end
  [f, t]
end


procedures = [[[1], 0, 0, [[0, 0]]], [[4], 0, 0, [[0, 0]]]]
while (pr = procedures.shift)
  case pr[0][-1]
  when 1 then pr[1] = B1
  when 4 then pr[2] = B2
  when 0 then pr[1] = 0
  when 3 then pr[2] = 0
  when 2
    pr[1], pr[2] = move(B2, pr[1], pr[2])
  when 5
    pr[2], pr[1] = move(B1, pr[2], pr[1])
  end
  
  if pr[1] == TO or pr[2] == TO
    p pr[0]
    next
  end
  
  next if pr[3].include?(a = [pr[1], pr[2]])
  pr[3] << a
  next if pr[1] == B1 and pr[2] == B2
  
  6.times do |i|
    a = pr[0].dup
    a << i
    procedures.push([a, pr[1], pr[2], pr[3]])
  end
end