plot

plot.rb

# A -> B
# C -> D
# B -> E
# A -> E
# E -> Y
# Y -> Z
# Z -> X

def routes
  {a: [:b, :e], c: [:d], b: [:e], e: [:y], y: [:z], z: [:x] }
end

def find(routes, start, finish, path)
  path += [start]
  return [path] if start == finish
  return  unless routes.has_key?(start)
  routes[start].map { |e| find(routes, e, finish, path) unless path.include?(e) }
end

def plot(start, finish)
  find(routes, start, finish, []).map {|p| p.flatten.compact.join(" -> ") }
end

puts plot(:a, :x) # ->
# a -> b -> e -> y -> z -> x
# a -> e -> y -> z -> x