COMP9024 Data Structures and Algorithms - Assignment 2: TripView
COMP9024 23T3
Change Log
Assignment TripView
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)
Due
5 marks for stage 2
(correctness)
2 marks for stage 3
(correctness)
1 mark for complexity
analysis
1 mark for style
———————
Total: 12 marks
5:00:00pm on Monday 13 November (week 10)
Late 5% penalty per day late (e.g. if you are 25 hours
Aim
late, your mark will be reduced by 10%)
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:
railway-station transfer-time
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:
./tripView
Size of network: 3HarrisPark
1
TownHall
3
NorthSydney 2
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:
scanf("%s", name);
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:
station hhmm
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: 3HarrisPark
0945
TownHall
1020
NorthSydney
1035
Number of stops: 2TownHall
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.
Each stop will be visited at most once in a single timetable.
All trains reach their final stop before midnight.
Trip View
The final input to your program are user queries:
From: HarrisPark
To: NorthSydney
Arrive at or before: 1200
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:
From: done Bye
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:
./tripView
Size of network: 7Ashfield
5
Central
8
HarrisPark 1 MilsonsPoint 2 NorthSydney 2
Redfern
5
TownHall
3
Number of timetables: 2
Number of stops: 5HarrisPark
0945
Ashfield
0955
Redfern
1006
TownHall
1020
NorthSydney
1035
Number of stops: 4Redfern
1359
Central
1406
TownHall
1410
MilsonsPoint
1430
From: Central
To: MilsonsPoint
Arrive at or before: 1600
1406 Central
1410 TownHall
1430 MilsonsPoint
From: Ashfield
To: NorthSydney
Arrive at or before: 1040
0955 Ashfield
1006 Redfern
1020 TownHall
1035 NorthSydney
From: done Bye
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:
./tripView
Size of network: 6Ashfield
5
Central
8
HarrisPark 1 NorthSydney 2
Redfern
5
TownHall
3
Number of timetables: 2
Number of stops: 5HarrisPark
0945
Ashfield
0955
Redfern
1006
TownHall
1020
NorthSydney
1035
Number of stops: 3HarrisPark
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
If there is no connection that satisfies the requirements, then the output should
be: No connection.
From: HarrisPark
To: TownHall
Arrive at or before: 1015
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:
./tripView
Size of network: 3HarrisPark
1
NorthSydney
2
TownHall
3
Number of timetables: 2
Number of stops: 3HarrisPark
0945
TownHall
1020
NorthSydney
1035
Number of stops: 2TownHall
1024
NorthSydney
1033
From: HarrisPark
To: NorthSydney
Arrive at or before: 1040
0945 HarrisPark
1020 TownHall
Change at TownHall
1024 TownHall
1033 NorthSydney
From: done Bye
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:
-
the size of the network, n
-
the number of timetables, m
-
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 list ADT : 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 dryrun 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:
9024 dryrun tripView
Please note: Passing dryrun does not guarantee that your program is correct. You should thoroughly test your program with your own test cases.
