This is a coding challenge from Adidas. You can find full details on https://bitbucket.org/adigsd/backend-flitetrakr.

The main purpose of the application is finding the best travel plans for a different set of airport connections. In order to do so, a set of flight details are provided and several questions can be answered, for example, which is the cheapest travel route between airports.

You can download the code (created on Eclipse) to build and run the application, or directly run the included jar file (Flite.jar).

If you run the jar file, you'll need to provide the input information either as a text file or as direct input to it:

• java -jar Flite.jar input.txt
• cat input.txt | java -jar Flite.jar

The input information should be:

• First line containing the existing flight connections and their prices. Line should start by Connections: and then each connection should have the format <code-of-departure-airport>-<code-of-arrival-airport>-<price-in-euro>. The connections will be separated by a comma and may have an optional space.
  • For example: Connections: AMS-PDX-617,NUE-AMS-123, AMS-LHR-43,LHR-HKG-1235, NUR-FRA-61, FRA-HKG-1087

• "What is the price of the connection ?".
  What is the price of the connection NUE-LHR-BOS?
• "What is the cheapest connection from to ?".
  What is the cheapest connection from AMS to DXB?"
• "How many different connections with maximum stops exist between and ?".
  How many different connections with maximum 3 stops exist between PDX and BOS?
• "How many different connections with exactly stops exist between and ?".
  How many different connections with exactly 2 stops exist between DXB and DXB?
• "Find all connections from to below Euros!".
  Find all connections from AMS to LHR below 2500Euros!

Each input line should start by "#" where n is the question number. This is used for reference when displaying the output:
#3: What is the price of the connection NUE-FRA-LHR-NUE?"

• "What is the price of the connection ?"
  If the route exists application will return the total cost of the route, with no formatting
  If the route doesn't exist application will return No such connection found!
• "What is the cheapest connection from to ?"
  Application will return the cheapest route including the total cost at the end of the route. For example, AMS-LHR-FRA-DXB-1347.
  If the route doesn't exist application will return No such connection found!.
  If the route source and destination airport is the same, it will look for the cheapeast route that starts and ends that airport, excluding not travelling. For example, it will return FRA-LHR-FRA-312 instead of FRA-FRA-0 for airport FRA.
• "How many different connections with maximum stops exist between and ?"
  The application will return the amount of routes available, being 0 a valid answer.
• "How many different connections with exactly stops exist between and ?"
  The application will return the amount of routes available, being 0 a valid answer.
• "Find all connections from to below Euros!"
  Application will print out all the available routes separated by comma and sorted by ascending price.

Let's view an example, given the following input:

Connections: NUE-FRA-43, NUE-AMS-67, FRA-AMS-17, FRA-LHR-27, LHR-NUE-23
#1: What is the price of the connection NUE-FRA-LHR?
#2: What is the price of the connection NUE-AMS-LHR?
#3: What is the price of the connection NUE-FRA-LHR-NUE?
#4: What is the cheapest connection from NUE to AMS?
#5: What is the cheapest connection from AMS to FRA?
#6: What is the cheapest connection from LHR to LHR?
#7: How many different connections with maximum 3 stops exists between NUE and FRA?
#8: How many different connections with exactly 1 stop exists between LHR and AMS?
#9: Find all connections from NUE to LHR below 170Euros!

This should print the following output:
#1: 70
#2: No such connection found!
#3: 93
#4: NUE-FRA-AMS-60
#5: No such connection found!
#6: LHR-NUE-FRA-LHR-93
#7: 2
#8: 1
#9: NUE-FRA-LHR-70, NUE-FRA-LHR-NUE-FRA-LHR-163

Guillermo Gonzalez - Zaragoza, Spain.

Probably not the best and elegant solution, but hey, it works! (or at least I think so :| ) Hopefully I'll be able to look at this in a few years time and be able to improve it far more. I've been working on python for a while now, so this is a fun exercise.