2018-08-02 Bits, Please! Code Fight

nightRoute.rb

def nightRoute(city)
  final = city.length - 1
  hops = {}
  hops[0] = city[0].each_with_index.map{ |length, island| length == -1 ? nil : [0, island] }.compact
  (1..final).each do |iter|
    hops[iter] = hops[iter - 1].map do |path|
      if path[-1] == final
        nil
      else
        city[path[-1]].each_with_index.map do |length, island|
          if length == -1
            nil
          elsif path.include?(island)
            nil
          else
            [*path].append(island)
          end
        end.compact
      end
    end.compact
    hops[iter].flatten!(1)
    hops[iter].reject! { |a| [*a].length != [*a].uniq.length } unless hops[iter].nil?
  end
  hops.compact!
  hops.transform_values! do |routes|
    routes.reject { |route| !route.include?(final) }
  end
  routeLengths(city, hops).min
end

def routeLengths(city, hops)
  lengths = []
  hops.values.each do |routes|
    routes.each do |route|
      lengths.append(routeLength(city, route))
    end
  end
  lengths
end

def routeLength(city, route)
  route_length = 0
  route.each_cons(2) do | bridge |
    route_length += city[bridge[0]][bridge[1]]
  end
  route_length
end