Practical Python Assignment: Tic-Tac-Toe

Christopher G. Healey

Due Date

Friday, September 8, 5:00pm via Moodle. Look for the "Practical Python Assignment: Tic-Tac-Toe" link.

Introduction

The second assignment for this year's Python module asks you to write a simple tic-tac-toe game that allows two players to play tic-tac-toe against one another. You will be asked to:

1. Implement a program that tracks the state of an ongoing tic-tac-toe game.
2. Allow each player to choose the position they want to place their pieces.
3. Check and end the game when either a win or a tie occurs.

Assignment Requirements

Your program must meet the following requirements, since it will be marked electronically, failing to meet these requirements means your program or its ouptut will not be found and cannot be graded.

1. Your program MUST be called tictactoe.py. You CANNOT submit a Jupyter notebook .ipynb file.
2. You MUST use the identifiers A1, A2 and so on to refer to squares on the board exactly as we have specified.

Basic Game Loop

The game loop for a tic-tac-toe game is fairly simple.

1. Initialize the board to be empty.
2. X starts, and chooses a position to place their marker.
3. O positions their marker in any empty position.
4. After each marker is placed, a check is made to see whether either player has won.
5. Placement alternates until a player wins or the board is full, at which point the game is called for a tie.

The reason you would break down the game like this isn't because you don't know tic-tac-toe, but because this gives you a fairly good idea of what you need to do to program Python to play a tic-tac-toe game. This is a common strategy for larger programs, take each problem and break it down into a sequence of sub-problems until you feel comfortable that you understand how to write code to solve each sub-problem. If our breakdown above is still too high level, keep decomposing it until to get to a point where you feel like you understand how to convert each description into a corresponding block of code.

Interface

Board Positions.  Because we'll be marking your programs electronically, there is a very specific way that positions on the board are labeled, and in how your program should accept the positions as input to update your tic-tac-toe board.

Positions on the board are labeled with the numbers 1, 2, and 3, used for the three rows, top to bottom, and the letters A, B, and C, used for the three columns, left to right. So, for example, the top-left position is A1, and the bottom-left position is C3. The entire board has positions labeled like this.

User Input.  When a user enters a position, they must use the above format exactly. You are required to check any position a user provides to ensure it properly defines a valid position. If it does not, you should tell the user the position is invalid, and ask them to enter a new, correct position.

Even if the position provided by the user is in the correct format, it may still be invalid (e.g., if the position is already taken). After confirming the position's format is correct, you must then check to ensure the position itself is available. If not, you would again report the issue to the user and ask them to provide a new, valid position.

Input from the keyboard can be requested using Python's input() function.

input() allows a user to enter characters from the keyboard, then returns the result as a string. This can be assigned to a variable for further processing.

Wins and Ties

At some point, one of the players will win the game, or the game will end in a tie. When this happens, your program should print the result of the game, and exit the program.

Grading

Each student must submit their Python code using Moodle. Look for "Python - Assignment 2 - Tic Tac Toe" in the Programming & Visualization → Python section. Remember, you MUST name your program tictactoe.py and you CANNOT submit a Jupyter notebook .ipynb file.

Your program will be graded on a 101-point scale from 0 to 100. Grading will be performed using an automated input script, so please remember it's important that your program accept the input format described in the Interface section of the assignment.

Collaboration

Because this is one of the first assignments where you will not be working in teams, I want to provide some guidelines on the types of collaboration that are considered acceptable and not acceptable for this assignment.

Acceptable collaboration would include:

• Discussing general design strategies to address problems in the assignment,
• Providing references to information in the documentation that could be helpful in completing the assignment, and
• Discussing general Python approaches to solving tasks that could occur in the assignment.

When you sit down to code your assignment, you will do this by yourself. You cannot collaborate with your classmates when you write your code. It must be done individually, and without assistance from other students that include:

• Having another classmate provide you with code, or providing code to your classmate(s),
• Having another classmate help debug your code, or helping debug a classmate(s) code,
• Obtaining specific code solutions to parts of the assignment from a classmate, or providing specific code solutions to parts of the assignment to your classmate(s), and
• Using any online or other resources that provide code solutions to significant portions of the assignment.

Submission of your code means you've implicitly agreed to these collaboration guidelines, and have not participated in any type of collaboration that would be considered inappropriate.

If you have any questions about whether a specific collaboration is allowed, please ask either myself or Andrea. We're happy to discuss where the lines lie with respect to how you can communicate with your classmates about the assignment.