Assignment #2
CSCI 201 Fall 2024
Page 1 of 11
Assignment #2
CSCI 201 Fall 2024
6% of course grade
Title
Networked Crossword Puzzle
Topics Covered
Networking 
Multi-Threading
Concurrency Issues
Introduction
This assignment will require you to create two different programs – a server and a client. You 
will implement a networked crossword puzzle game where multiple users can play against each 
other. There will be some concurrency issues since you will need to make sure only certain 
clients can play at different times. There will be many ways to design out the program, so I 
recommend you spend some time designing it out on paper before you begin coding.
Crossword puzzle game
A crossword puzzle is a word game consisting of interlocking horizontal and vertical grids. 
Participants enter letters into these grids based on the provided clues. The game concludes when 
all empty grids are correctly filled. Typically, the horizontal grids are referred to as ACROSS 
entries, while the vertical grids are called DOWN entries. Each across or down entry, which 
consists of a series of grids, corresponds to a word or phrase. All entries are indexed, and the 
corresponding clues are provided for the participants. Additionally, the intersection of an across 
entry and a down entry indicates a shared letter at that specific location, which usually serves as 
an extra hint besides the entry-specific clues.
Crossword puzzle game example
Assignment #2
CSCI 201 Fall 2024
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Server Functionality
The server will be responsible for reading the puzzle data from a file and distributing it to the 
clients when they connect. To simplify execution of your program, only one game can be 
occurring at a time. Each game will have between 1 and 3 players. The first client to connect to 
the server will specify the number of players.
The server will have (possibly) multiple puzzle data files in a directory called gamedata at the 
top of your project directory. Make sure that you specify a relative path when reading the puzzle
data files so the graders can drop their puzzle data files in the gamedata directory and run your
program without having to change any hard-coded variables. Your server program will need to
open the directory that contains all the puzzle data files and determine how many files are in that 
directory. It will then randomly choose one of the files to use. Of course, if there is only one file 
in the directory, that is the one that will be chosen. The names of the files are irrelevant since the 
server will choose one of them randomly, so they could be named anything at all.
Each game data file will contain all the information needed to play a game. The file will be 
formatted as a Comma Separated Value (CSV) file with ACROSS on the first line, followed by one
or more lines formatted as:
ACROSS,,
<number>,<answer>,<question>
The file will then have a line with the word DOWN, then one or more lines formatted the same as 
above. Here is a sample file:
ACROSS,,
1,trojans,What is USC’s mascot?
2,dodgers,What professional baseball team is closest to USC? 
3,csci,What is the four-letter prefix for Computer Science? 
DOWN,,
1,traveler,What is the name of USC’s white horse? 
4,gold,What is one of USC’s colors?
5,marshall,Who is USC’s School of Business named after?
Your server program will need to determine if the file is formatted properly. The only rules that 
you need to check are the following:
1. The words ACROSS and DOWN exist on their own lines and only one time in the file and
are followed by empty CSV fields. 
2. The other lines in the file are formatted with three parameters – integer, answer, question.
a. The three parameters are separated by commas as it is normal for CSV files.
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CSCI 201 Fall 2024
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3. If a number in the ACROSS section matches a number in the DOWN section, the 
answers must start with the same letter. In the example above, the lines with 
trojans and traveler both start with same letter “t”, since their number is 
the same, “1”.
4. An answer cannot contain any whitespace.
5. Questions normally will contain whitespace.
The server will need to determine how to format the answers in the game board so it can send out 
that information to all the clients (since the clients all need to render the game board the same).
There will be different ways that the data can be rendered. You can assume that there is at least 
one viable way to render the game board. In other words, you can assume that each word 
contains at least one letter that is in another word and the board can be rendered for the player. 
This may be challenging to figure out, so make sure to write out an algorithm to solve this before 
you begin coding.
If the ACROSS number and the DOWN number are the same, that means the answers will start 
with the same letter, as explained above. The numbers do not have to be in order in the file, but 
all the questions for a section will immediately follow the lines with ACROSS or DOWN.
There will not be more than one ACROSS or DOWN section in a file.
All the answers to the questions are case-insensitive. The server will wait to randomly 
determine a game file to read until the first client has connected.
The server will listen on port 3456. When a client connects to it, it will randomly determine a 
game data file to read, verify that the file is formatted properly, and figure out a rendering of the
game board. If there are no valid game files, the server should report that to the client and
continue waiting for another client to connect. At that point, it will read the directory again and 
randomly choose another game data file.
When the first client connects to it, the first message it sends will be a number between 1 and 3 
to determine how many players will be part of the game. If the number is 1, the server can start 
the game. If the number is 2 or 3, the server will need to wait until the proper number of clients 
have connected to the server before starting the game.
Game Play
Once the proper number of players have joined the game, the server will send out the game board 
to all the players. The players will begin play in the order they joined the game. Only one player 
should be able to play at a time. More information on how the client will behave is included in 
the relevant section below. Every play should be sent to the server. The server validates
whether the answer provided for the appropriate question is correct. If it is, the same player who 
guessed the correct answer will get to play again. If it is incorrect, play will proceed to the next 
player. Regardless, the server should send a notification to all the clients letting them know what 
Assignment #2
CSCI 201 Fall 2024
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question the player was attempting to answer, what the player guessed, and whether it was 
correct.
The server should keep track of how many correct answers each player has guessed, and which 
questions are remaining. Once all the questions have been answered correctly, the server will 
notify all the players of the final score (1 point for each question answered correctly) and who 
the winner is (or a tie, if that is the case).
You do not need to maintain statistics, and there are no user accounts. Once a game concludes, 
the clients should terminate. The server should loop and allow a new game to begin by having 
another client connect. The server cannot allow another game to begin while a game is being 
played – only one game is played at a time. The server should never have to be restarted, 
though, to play subsequent games. Once the server has started, the only way to stop playing 
games is to “kill” the server, which is done by clicking “Terminate”, the red square, in Eclipse. 
Client Functionality
The client will begin by welcoming the user to the game and prompting them for the server 
hostname and port. If a valid connection is not made, an error message should be displayed, and 
the client should loop back to allow the user to enter another server hostname and port. If a valid 
connection is made, the first client should prompt for the number of players. The valid number
of players is between 1 and 3. The first client should continue prompting for the number of 
players until a valid number is entered.
If the necessary number of players have not yet joined the game, all the clients, except for the 
last one to join, should display a message that says “Waiting for player x.” The “x” 
should be replaced by the player number for which we are waiting. When a player joins, all 
clients, except for the last one, should display a message stating from which IP address the player
joined.
Once all the required players have joined, all clients should display a message that says, “The
game is beginning.” The server will send the game board, which includes the crossword 
puzzle and the questions.
Play will proceed through the players based on the order they joined the game. Player 1 will go 
first and select to guess the answer to a question that is either “down” or “across”, as in “Would
you like to answer a question across (a) or down (d)?”. If “d” or “a” is not 
entered, the client should prompt the user again. The user will then be prompted to enter a 
number for which question to answer, as in “Which number?”. If the value entered is not 
valid, the client should prompt the user again.
Once the user has entered a valid question, (let’s assume “a” and “1” were entered), the client 
should prompt the user to enter the answer to the question, “What is your guess for 1 
Assignment #2
CSCI 201 Fall 2024
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across?” The answer should be sent to the server, which will return whether it was correct or 
incorrect to all the connected clients. The (possibly) updated game board and remaining
questions to answer will be sent to all clients. Do not display questions that have already been 
answered correctly.
If a player answers a question correctly, they will get to answer another question. If the answer 
was incorrect, play will move to the next client who joined. If the last player that joined answers 
a question incorrectly, play will proceed with the first player.
Play continues until all the correct answers have been guessed. The completed game board with
all the questions will be displayed, and the final scores will be shown. The final score is only 
based on how many questions a user guessed correctly. If one player has more correct answers 
than any the others, that player is declared the winner. If two players have the same score, the 
game is declared as a tie.
All the clients will then terminate, but the server will loop back to allow new players to join and 
start a new game.
The sample execution that follows shows all the messages that should be displayed throughout 
the game. Your output should be as close as possible to the one shown below, though the
crossword puzzle may look different for the same answers since that will be based on how your 
program generates it.
Assignment #2
CSCI 201 Fall 2024
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Sample Execution
Below is a sample execution of the program with the user input in bold red (though the input
will not be bolded, or colored, when you run your program). The first column is the server, the 
second column is the first player, and the third column is the second player. Ignore all the extra 
blank lines that are displayed, to try to show you the timeline at which output is generated, but in 
the actual output, all the lines will be displayed next to each other. This sample run is using the 
sample puzzle game file that was provided earlier in the assignment.
Server Player 1 Player 2
Listening on port 3456.
Waiting for players...
Welcome to 201 Crossword!
Enter the server hostname: localhost
Enter the server port: 3456
Connection from 127.0.0.1
How many players will there be? 2
Number of players: 2 
Waiting for player 2. 
Reading random game file.
File read successfully.
Waiting for player 2.
Welcome to 201 Crossword!
Enter the server hostname:
localhost
Enter the server port: 3456
Connection from 127.0.0.1
Player 2 has joined from 127.0.0.1. There is a game waiting for you.
Player 1 has already joined.
Game can now begin.
The game is beginning. The game is beginning.
Sending game board. 5_
Across
1 What is USC’s mascot?
2 What professional baseball team is 
closest to USC?
3 What is the four-letter prefix for 
Computer Science?
Down
1 What is the name of USC’s white 
horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business
named after?
Across
1 What is USC’s mascot?
2 What professional baseball team
is closest to USC?
3 What is the four-letter prefix
for Computer Science?
Down
1 What is the name of USC’s white 
horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business
named after?
Assignment #2
CSCI 201 Fall 2024
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Player 1’s turn.
Would you like to answer a question 
across (a) or down (d)? d
That is not a valid option?
Would you like to answer a question 
across (a) or down (d)? a
Which number? 4
That is not a valid option. 
Which number? 1
What is your guess for 1 across?
trojans
Player 1’s turn.
Player 1 guessed “trojans” for 
1 across.
Player 1 guessed “trojans” for 1 
across.
That is correct.
That is correct. That is correct.
Sending game board.
Across
2 What professional baseball team is 
closest to USC?
3 What is the four-letter prefix for 
Computer Science?
Down
1 What is the name of USC’s white 
horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business 
named after?
Across
2 What professional baseball team
is closest to USC?
3 What is the four-letter prefix
for Computer Science?
Down
1 What is the name of USC’s
white horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business 
named after?
Player 1’s turn.
Would you like to answer a question 
across (a) or down (d)? d
Which number? 1
What is your guess for 1 down? Trav
Player 1 guessed “Trav” for 1 
down.
Player 1 guessed “Trav” for 1 
down.
That is incorrect.
That is incorrect. That is incorrect.
Sending game board.
Assignment #2
CSCI 201 Fall 2024
Across
2 What professional baseball team is 
closest to USC?
3 What is the four-letter prefix for 
Computer Science?
Down
1 What is the name of USC’s white 
horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business 
named after?
Across
2 What professional baseball team is 
closest to USC?
3 What is the four-letter prefix for 
Computer Science?
Down
1 What is the name of USC’s white 
horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business 
named after?
Players 2’s turn.
Players 2’s turn. Would you like to answer a question 
across (a) or down (d)? d
Which number? 1
What is your guess for 1 down?
traveler
Player 2 guessed “traveler” 
for 1 down.
Player 2 guessed “traveler” for 1 
down.
That is correct.
That is correct. That is correct.
Sending game board.
Across
2 What professional baseball team is 
closest to USC?
3 What is the four-letter prefix for 
Computer Science?
Down
1 What is the name of USC’s white 
horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business 
named after?
Across
2 What professional baseball team is 
closest to USC?
3 What is the four-letter prefix for 
Computer Science?
Down
1 What is the name of USC’s white 
horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business 
named after?
Assignment #2
CSCI 201 Fall 2024
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Player 2’s turn.
Player 2’s turn. Would you like to answer a question 
across (a) or down (d)?
<Play continues until all questions have been answered correctly.>
<Assume everything has been answered correctly except 2 across, and it’s player 1’s turn.>
Sending game board.
2 What professional baseball team is
closest to USC?
Across
2 What professional baseball team is
closest to USC?
Player 1’s turn.
Would you like to answer a question 
across (a) or down (d)? d
That is not a valid option.
Would you like to answer a question 
across (a) or down (d)? a
Which number? 2
What is your guess for 2 across?
Dodgers
Player 1’s turn.
Player 1 guessed “Dodgers”
for 2 across.
Player 1 guessed “Dodgers” for 2
across.
That is correct.
That is correct. That is correct.
Sending game board.
Across
1 What is USC’s mascot?
Across
1 What is USC’s mascot?
Assignment #2
CSCI 201 Fall 2024
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The game has concluded. 
Sending scores.
Waiting for players...
2 What professional baseball team is 
closest to USC?
3 What is the four-letter prefix for 
Computer Science?
Down
1 What is the name of USC’s white 
horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business 
named after?
Final Score
Player 1 – 4 correct answers.
Player 2 – 2 correct answers. 
Player 1 is the winner.
<Client terminates>
2 What professional baseball team is 
closest to USC?
3 What is the four-letter prefix for 
Computer Science?
Down
1 What is the name of USC’s white 
horse?
4 What is one of USC’s colors?
5 Who is USC’s School of Business 
named after?
Final Score
Player 1 – 4 correct answers.
Player 2 – 2 correct answers. 
Player 1 is the winner.
<Client terminates>
Assignment #2
CSCI 201 Fall 2024
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Grading Criteria
The way you go about implementing the solution is not specifically graded, but the output must 
match exactly what you see in the execution above. The maximum number of points earned is 
5.
Networking (0.5)
0.1 - first client can connect to server
0.2 - only the number of clients as specified by first client can connect to server
0.2 - server allows a new game to be played after previous one ends without restarting
File Reading (0.5)
0.1 - random file chosen from gamedata directory 
0.1 - gamedata directory is at the top of the project folder
0.1 - server chooses game data file after first client connects 
0.2 - client is notified if no valid game data file exists
Game Board Rendering (1.5)
1.5 - game board is rendered in a correct manner where there are no disjoint words (i.e., they are all 
connected to each other)
Game Play (1.5)
0.1 - only one player can answer a question at a time
0.1 - once a question has been answered correctly, that question is no longer displayed 
0.1 - answers are case-insensitive
0.1 - proper error checking is in place for “a” and “d”
0.1 - proper error checking is in place for the question number to answer 
0.2 - all clients are notified of answers that are guessed by other players 
0.1 - updated game board is displayed properly
0.3 - final score is displayed after all answers have been guessed correctly 
0.1 - client terminates after the final score is displayed
0.3 - the game is played as expected with no exceptions, crashing, deadlock, starvation, or freezing
Output (0.4)
0.4 - the output is the same as what is provided in the sample above
Synchronization (0.6)
0.3 - synchronization through monitors, locks, or semaphores is used somewhere in the server 
0.3 - synchronization through monitors, locks, or semaphores is used somewhere in the client

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