COMP9024 23T3 - Assignment

Change Log

We may make minor changes to the spec to address/clarify some outstanding issues. These may

require minimal changes in your design/code, if at all. Students are strongly encouraged to check the change log regularly.

Version 1: Released on 20 October 2023

Objectives

The assignment aims to give you more independent, self-directed practice with

advanced data structures, especially graphs

graph algorithms

asymptotic runtime analysis

Admin

Marks 3 marks for stage 1 (correctness)

5 marks for stage 2 (correctness)

2 marks for stage 3 (correctness)

1 mark for complexity analysis

1 mark for style

Total: 12 marks

Due 5:00:00pm on Monday 13 November (week 10)

Late 5% penalty per day late

(e.g. if you are 25 hours late, your mark will be reduced by 10%)

Aim

The objective is to write a program tripView.c that generates an optimal trip on (a part of) Sydney's railway network based on user preferences.

Input

Railway stations

The first input to your program consists of an integer n > 0, indicating the number of railway stations on the network, followed by n*2 lines of the form:

where the first line is the name of a station and the second line denotes the time – in minutes – it takes to transfer to a different train at that station.

Here is an example:

prompt$ ./tripView

Size of network: 3

You may assume that:

The input is syntactically correct.

The maximum length (strlen()) of the name of a railway station is 16 and will not use any

spaces.

The transfer time will be a positive integer.

No name will be input more than once.

Hint:

To read a single line with a station name you should use:

where  name is a string, i.e. an array of  chars.

Timetables

The next input to your program is an integer m > 0, indicating the number of trains on any day, followed by m timetables. Each timetable starts with the number s > 1 of stops followed by s *2 lines of the form:

meaning that you can get on or off the train at that station at the given time (hh – hour, mm – minute).

Here is an example:

Number of timetables: 2

Number of stops: 3

HarrisPark

0945

TownHall

1020

NorthSydney

1035

Number of stops: 2

TownHall

1024

NorthSydney

1033

You may assume that:

The input is syntactically correct.

All times are given as 4 digits and are valid, ranging from 0000 to 2359.

Only train stations that have been input earlier as part of the network will be used. The stops are input in the correct temporal order.

All trains reach their final stop before midnight.

Trip View

The final input to your program are user queries:

As before, you may assume that the input is correct: Two different valid railway stations followed by a valid time in the form of 4 digits.

Your program should terminate when the user enters  "done"  when prompted with  From:

Stage 1 (3 marks)

Stage 1 requires you to generate a suitable data structure from the input.

Test cases for this stage will only use queries   FromStation, ToStation, ArrivalTime such that:

there exists one, and only one, train that travels from   FromStation to  ToStation ;

this train arrives on, or before, the given  ArrivalTime ; and

this train is the desired output for the query.

Therefore, at this stage all you need to do is find and output the connection between the two train stations, including all the stops along the way and the arrival/departure times.

Here is an example to demonstrate the expected behaviour of your program for a stage 1 test:

Stage 2 (5 marks)

For the next stage, your program should find and output a connection from   FromStation to ToStation that:

may involve one or more train changes;

arrives at  ToStation no later than  ArrivalTime ; and

leaves as late as possible.

Note that you can get onto a different train at any station, but it is necessary to take into account the time it takes to change trains at that station.

In all test scenarios for this stage there will be at most one connection that satisfies all requirements. Here is an example to demonstrate the expected behaviour of your program for stage 2:

Number of stops: 5

HarrisPark

0945

Ashfield

0955

Redfern

1006

TownHall

1020

NorthSydney

1035

Number of stops: 3

HarrisPark

0950

Central

1010

TownHall

1017

From: HarrisPark

To: NorthSydney

Arrive at or before: 1040

0950 HarrisPark

1010 Central

1017 TownHall

Change at TownHall

1020 TownHall

1035 NorthSydney

From: done

Bye

prompt$

If there is no connection that satisfies the requirements, then the output should be:  No connection.

Stage 3 (2 marks)

For the final stage, if there are multiple possible connections with the same latest departure time, your program should take into account the additional user preference that:

among all the connections with the latest possible departure time, choose the one with the shortest overall travel time.

You may assume that there will never be more than one connection with the latest possible departure  time and the shortest overall travel time. Note also that travel time includes the time it takes to change trains and the waiting time if applicable.

Here is an example to demonstrate the expected behaviour of your program for stage 3:

Complexity Analysis ( 1 mark)

You should include a time complexity analysis for the asymptotic worst-case running time of your program, in Big-Oh notation, depending on the size of the input:

1. the size of the network, n

2. the number of timetables, m

3. the maximum number of stops on any one timetable, s.

Hints

If you find any of the following ADTs from the lectures useful, then you can, and indeed are encouraged to, use them with your program:

linked listADT : list.h, list.c

stack ADT : stack.h, stack.c

queue ADT : queue.h, queue.c

priority queue ADT : PQueue.h, PQueue.c

graph ADT : Graph.h, Graph.c

weighted graph ADT : WGraph.h, WGraph.c

You are free to modify any of the six ADTs for the purpose of the assignment (but without

changing the file names). If your program is using one or more of these ADTs, you should submit both the header and implementation file, even if you have not changed them.

Your main program file tripView.c should start with a comment: /* … */ that contains the time complexity of your program in Big-Oh notation, together with a short explanation.

Testing

We have created a script that can automatically test your program. To run this test you can execute the dry run program that corresponds to this assignment. It expects to find, in the current directory, the program tripView.c and any of the admissible ADTs

(Graph,WGraph,stack,queue,PQueue,list) that your program is using, even if you use them unchanged. You can use dryrun as follows:

prompt$ 9024 dry run tripView

Please note: Passing dryrun does not guarantee that your program is correct. You should thoroughly test your program with your own test cases.