5-sided die

I know! I'll use my
Higher-order functions to
Order higher rolls.


This is an alternate "extreme" version of the standard hog project that gives you much less guidance than the normal version. It is only appropriate for students with substantial prior programming experience. Completing this version of the project is equivalent to completing the standard version of Project 1.

The rules of the game of Hog are the same as the standard project.

You should not expect much assistance from staff if you choose to complete this version of the project. You can always switch to the standard version if you get stuck.

Download starter files

To get started, download all of the project code as a zip archive. You only have to make changes to hog.py.

  • hog.py: A file containing stubs of the functions you must implement
  • dice.py: Functions for rolling dice
  • hog_gui.py: A graphical user interface for Hog
  • ucb.py: Utility functions for CS 61A
  • ok: CS 61A autograder
  • hog_eval.py: Utility for evaluating the Hog project
  • tests: A directory of tests used by ok
  • images: A directory of images used by hog_gui.py


This is a 1-week project. You may work with one other partner. You should not share your code with students who are not your partner or copy from anyone else's solutions.

In the end, you will submit one project for both partners. The project is worth 20 points. 18 points are assigned for correctness, and 2 points for the overall composition of your program.

You will turn in the following files:

  • hog.py

You do not need to modify or turn in any other files to complete the project. To submit the project, run the following command:

python3 ok --submit

You will be able to view your submissions on the OK dashboard.

For the functions that we ask you to complete, there may be some initial code that we provide. If you would rather not use that code, feel free to delete it and start from scratch. You may also add new function definitions as you see fit.

However, please do not modify any other functions. Doing so may result in your code failing our autograder tests. Also, please do not change any function signatures (names, argument order, or number of arguments).


Throughout this project, you should be testing the correctness of your code. It is good practice to test often, so that it is easy to isolate any problems.

We have provided an autograder called ok to help you with testing your code and tracking your progress. The first time you run the autograder, you will be asked to log in with your OK account using your web browser. Please do so. Each time you run ok, it will back up your work and progress on our servers.

The primary purpose of ok is to test your implementations, but there is a catch. At first, the test cases are locked. To unlock tests, run the following command from your terminal:

python3 ok -u

This command will start an interactive prompt that looks like:

Assignment: The Game of Hog Extreme Version
OK, version ...

Unlocking tests

At each "? ", type what you would expect the output to be.
Type exit() to quit

Question 0 > Suite 1 > Case 1
(cases remaining: 1)

>>> Code here

At the ?, you can type what you expect the output to be. If you are correct, then this test case will be available the next time you run the autograder.

The idea is to understand conceptually what your program should do first, before you start writing any code.

Once you have unlocked some tests and written some code, you can check the correctness of your program using the tests that you have unlocked:

python3 ok

Most of the time, you will want to focus on a particular question. Use the -q option as directed in the problems below.

The tests folder is used to store autograder tests, so make sure not to modify it. You may lose all your unlocking progress if you do. If you need to get a fresh copy, you can download the zip archive and copy it over, but you will need to start unlocking from scratch.

Graphical User Interface

A graphical user interface (GUI, for short) is provided for you. At the moment, it doesn't work because you haven't implemented the game logic. Once you complete the play function, you will be able to play a fully interactive version of Hog!

In order to render the graphics, make sure you have Tkinter, Python's main graphics library, installed on your computer. Once you've done that, you can run the GUI from your terminal:

python3 hog_gui.py

Once you complete the project, you can play against the final strategy that you've created!

python3 hog_gui.py -f

Phase 1: Simulator

In the first phase, you will develop a simulator for the game of Hog.

Problem 0 (0 pt)

The dice.py file represents dice using non-pure zero-argument functions. These functions are non-pure because they may have different return values each time they are called. The documentation of dice.py describes the two different types of dice used in the project:

  • Dice can be fair, meaning that they produce each possible outcome with equal probability. Examples: four_sided, six_sided.
  • For testing functions that use dice, deterministic test dice always cycle through a fixed sequence of values that are passed as arguments to the make_test_dice function.

Before we start writing any code, let's understand the make_test_dice function by unlocking its tests.

python3 ok -q 00 -u

This should display a prompt that looks like this:

Assignment: Project 1: Hog
OK, version v1.3.32

Unlocking tests

At each "? ", type what you would expect the output to be.
Type exit() to quit

Question 0 > Suite 1 > Case 1
(cases remaining: 1)

>>> test_dice = make_test_dice(4, 1, 2)
>>> test_dice()

You should type in what you expect the output to be. To do so, you need to first figure out what test_dice will do, based on the description above.

Note: you can exit the unlocker by typing exit() (without quotes). Typing Ctrl-C on Windows to exit out of the unlocker has been known to cause problems, so avoid doing so.

Problem 1 (8 pt)

Implement the play function, which simulates a full game of Hog. Players alternate turns, each using their respective strategy function (Player 0 uses strategy0, etc.), until one of the players reaches the goal score. When the game ends, play returns the final total scores of both players, with Player 0's score first, and Player 1's score second.

Here are some hints:

  • Enforce all the special rules.
  • A strategy is a function that, given a player's score and their opponent's score, returns how many dice the player wants to roll. A strategy function (such as strategy0 and strategy1) takes two arguments: scores for the current player and opposing player. A strategy function returns the number of dice that the current player wants to roll in the turn. Don't worry about details of implementing strategies yet. You will develop them in Phase 2.
  • On each turn, You must call the six_sided_dice or four_sided_dice function exactly the number of times that the player chooses to roll (even if a 1 is rolled part way through), in order to simulate rolling all dice simultaneously in the game (otherwise tests and the GUI will fail).

Before writing any code, unlock the tests to verify your understanding of the question:

python3 ok -q 01 -u

Once you are done unlocking, begin implementing your solution. You can check your correctness with:

python3 ok -q 01

Note: the last test for Question 1 is a fuzz test, which checks your play function works for any arbitrary inputs. Failing this test means something is wrong, but you should look at other tests to see where the problem might be.

Hint: If you fail the fuzz test, check that you're only calling take_turn once per turn!

Once you are finished, you will be able to play a graphical version of the game. We have provided a file called hog_gui.py that you can run from the terminal:

python3 hog_gui.py

If you don't already have Tkinter (Python's graphics library) installed, you'll need to install it first before you can run the GUI.

The GUI relies on your implementation, so if you have any bugs in your code, they will be reflected in the GUI. This means you can also use the GUI as a debugging tool; however, it's better to run the tests first.

Congratulations! You have finished Phase 1 of this project!

Phase 2: Strategies

In the second phase, you will design a final strategy to beat the "computer" who will only roll the same number of dice each time.

Problem 2 (2 pt)

Before you begin writing your final strategy, you need to have a way to evaluate its effectiveness.

Implement the make_averaged function, which is a higher-order function that takes a function fn as an argument. It returns another function that takes the same number of arguments as fn (the function originally passed into make_averaged). This returned function differs from the input function in that it returns the average value of repeatedly calling fn on the same arguments. This function should call fn a total of num_samples times and return the average of the results.

To implement this function, you need a new piece of Python syntax! You must write a function that accepts an arbitrary number of arguments, then calls another function using exactly those arguments. Here's how it works.

Instead of listing formal parameters for a function, we write *args. To call another function using exactly those arguments, we call it again with *args. For example,

>>> def printed(fn):
...     def print_and_return(*args):
...         result = fn(*args)
...         print('Result:', result)
...         return result
...     return print_and_return
>>> printed_pow = printed(pow)
>>> printed_pow(2, 8)
Result: 256
>>> printed_abs = printed(abs)
>>> printed_abs(-10)
Result: 10

Read the docstring for make_averaged carefully to understand how it is meant to work.

Before writing any code, unlock the tests to verify your understanding of the question:

python3 ok -q 02 -u

Once you are done unlocking, begin implementing your solution. You can check your correctness with:

python3 ok -q 02

Problem 3 (2 pt)

Implement the max_scoring_num_rolls function, which runs an experiment to determine the number of rolls (from 1 to 10) that gives the maximum average score for a turn. Your implementation should use make_averaged and roll_dice.

Note: If two numbers of rolls are tied for the maximum average score, return the lower number. For example, if both 3 and 6 achieve a maximum average score, return 3.

Before writing any code, unlock the tests to verify your understanding of the question:

python3 ok -q 03 -u

Once you are done unlocking, begin implementing your solution. You can check your correctness with:

python3 ok -q 03

To run this experiment on randomized dice, call run_experiments using the -r option:

python3 hog.py -r

Running experiments For the remainder of this project, you can change the implementation of run_experiments as you wish. By calling average_win_rate, you can evaluate various Hog strategies. For example, change the first if False: to if True: in order to evaluate always_roll(8) against the baseline strategy of always_roll(5). You should find that it loses more often than it wins, giving a win rate below 0.5.

Some of the experiments may take up to a minute to run. You can always reduce the number of samples in make_averaged to speed up experiments.

Problem 4 (6 pt)

Implement final_strategy, which combines these ideas and any other ideas you have to achieve a win rate of at least 0.77 (for full credit) against the baseline always_roll(5) strategy. Partial credit is also given if you are close. Some ideas:

  • Take advantage of the special rules.
  • Don't swap scores when you're winning.
  • There's no point in scoring more than 100. Check for chances to win.

You can check your final strategy win rate by running OK.

python3 ok -q 04

You can also play against your final strategy with the graphical user interface:

python3 hog_gui.py -f

The GUI will alternate which player is controlled by you.

Congratulations, you have reached the end of your first CS 61A project!