Homework Policies

The course staff must critically examine tens of thousands of pages of homework submissions this semester! We desperately need your help to make sure homeworks are graded fairly and returned quickly. If you have any questions or concerns about these policies, please don't hesitate to ask in lecture, in lab, during office hours, on Ed Discussion, or on Discord.

• What homework is for
• No late homework
• Don't plagiarize!
• Deadly Sins

• Logistics: How to submit
• Form: How to write
• Content: What to write

I apologize in advance for the length of this document. Most of this stuff is obvious to almost everybody, but after teaching algorithms for a couple of decades, I've seen a lot of strange things.

Homework handouts and solutions are available on a different page.

What homework is for

Algorithm design and analysis is a set of skills that can only be developed through practice and feedback, just like cooking or basketball or integration or gardening or interviewing or teaching. Yes, there are several things that are useful to know and understand, but that knowledge and understanding is not enough. That comfortable feeling of "Oh, sure, I get it" when you watch a well-presented lecture, hear a TA carefully explain a homework solution, or read a solution written by Gemini or Claude, is a seductive, dangerous trap. You can only learn to do the thing by actually doing the thing.

The homework is your opportunity to practice doing the thing. The lectures and textbook and office hours and labs and guided problem sets hopefully provide good intuition and motivation and justification for the skills we want you to develop, but the best way to develop those skills is by trying to solve the problems yourself. The practice is far more important than the solution.

We aren't really asking you for solutions; we already have solutions. We're asking for examples of your skill in developing solutions, so that we can just you feedback to help you improve.

Because the homework is intended to help you develop new skills, you are likely to get stuck; for some problems, you may have no idea how to even start. And that's okay. Getting stuck is completely normal, even for experts. That's why we have office hours and a textbook and lecture videos and PrairieLearn and Discord and a library and Wikipedia; helping you get unstuck is part of our job. That's why we encourage you to work together; not so that you can share solutions, but so that you can share ideas and suggestions and feedback.

Similarly, you won't necessarily develop a complete solution to every homework problem yourself, and you may not be able to tell at first which parts of your final submitted solution are correct. And that's also okay. Asking for help is normal, even for experts. That's why we provide homework solutions—not just to show you the answer, but to help you see your own work more clearly. That's why we grade your homework submissions—not to give you points, but to give you feedback to help you improve.

To get the most out of any particular homework problem, it's important not just to aim for a solution to that specific problem, but to pay attention to how you're solving it. Every problem is an opportunity to practice that kind of problem. And I don't just mean every assigned homework problem; that includes every problem presented in class; every problem described in the textbook or notes, every lab problem, every solved problem in the homeworks, and even every exam problem.

It's also important to aim for improvement—not perfection (which is impossible), not being better than other people (which can be toxic), but doing the thing better than you did yesterday, every day.

In practice, course grades in CS 374 are determined almost entirely by exams, which ask you to demonstrate the skills that the homework is meant to develop. Ultimately, homework scores have minimal impact. Even if your only goal is to optimize your course grade, practicing with the homework problems—developing both your skill and your confidence in that skill—is more important than getting the right answers.

No Late Homework

• Gradescope automatically stops accepting submissions at the deadline (Tuesday at 9pm). You can replace your submission as often as you like before the deadline; only your last submission before the deadline will actually be graded. We strongly recommend submitting something well before the deadline, to avoid any last-second emergencies.
• PrairieLearn will continue to accept and score submissions on guided problem sets after the deadline (Monday at 9pm), but only answers submitted before the deadline contribute to your course grade.
• To offset this rather draconian lateness policy, we have adopted a liberal policy of keeping only the highest homework and guided-problme-set scores when calculating final grades.
• We may forgive coursework under extreme circumstances that prevent the submission of a significant fraction of the homework, such as a documented disability, illness, injury, or other emergency. We will compute your final course grade as if your forgiven assignments do not exist; your other coursework will have more weight. Students requiring accommodation for a disability should first contact DRES. Please ask Jeff for further details.

Deadly Sins

We've identified a small number of bad writing (and thinking) habits that are strongly correlated with poor performance in algorithms courses, but are easy to avoid. Homework and exam solutions that commit any of these sins will be penalized. We’re not trying to be scary or petty (Honest!), but we do want to break a few common bad habits that seriously impede mastery of the course material.

• Don't cheat. You must write everything in your own words, and properly cite every outside source you use, including other students. Using ideas from other sources or people without citation is plagiarism. Copying other sources verbatim, even with proper citation, even with their permission, is plagiarism. Don't do that. See our academic integrity policies for more information.
• Write general solutions, not examples. Don't describe algorithms by showing the first two or three iterations and then writing “and so on”. Similarly, don't try to prove something by demonstrating it for a few small examples and then writing “do the same thing for all n”. Any solution that includes phrases like “and so on”, “etc.”, “do this for all n”, or “repeat this process” automatically gets a score of zero. Those phrases indicate precisely where you should have used iteration, recursion, or induction but didn’t.
• Don't submit code. You are not designing algorithms for the compiler. You are designing algorithms for a fluent programmer who doesn't share your intuition, training. or intelligence, and who thinks your favorite programming language sucks—someone like Jeff, or you three months from now. Describe your algorithms using structured English and/or pseudocode. Bare code with no English explanation automatically gets a grade of zero, even if it is correct.

  More generally, explain what you're doing. Whenever you introduce a new abstract object, explain in English what it means. When you describe a graph, specify in English the purpose/meaning of each vertex and edge. Whenever you describe an algorithm, specify in English precisely what problem your algorithm is trying to solve. Whenever you give a recurrence, describe in English precisely what function the recurrence is supposed to compute.

  You should already be doing this whenever you write code. After all, code is never written primarily for the compiler. Code is written primarily for the next programmer, who doesn't share your intuition, training. or intelligence, and who probably think your favorite programming lagnuage sucks. You know, you in three months.
  Just keep doing it.

Logistics: How to submit

• Submit homework solutions as PDF files on Gradescope. Submit one PDF file for each numbered homework problem. Gradescope will not accept other text file formats such as plain text, HTML, LaTeX source, or Microsoft Word (.doc or .docx). Homework submitted as images (.png or .jpg) will not be graded.
• Groups of at most three students can submit group solutions. We strongly encourage (but will not require) every student to work in a group with at least one other student. Students are responsible for forming their own homework groups. Groups may be different for each numbered homework problem. Gradescope automatically limits groups to at most three students.
  • Exactly one member of each group submits the solution to each problem. Even if the groups are identical, the submitter may be different for each numbered homework problem.
  • The submitter also tells Gradescope the names of the other group members. (The other group members must have already enrolled on Gradescope.) Gradescope then automatically applies the grade for that submission to everyone in the group. If this information is not entered correctly, the other group members' grades can be delayed or lost entirely.
  • The submitter also selects which pages are relevant for each lettered subproblem ((a), (b), etc.).
• As error correction, each submitted PDF file should include the following information in large friendly letters at the top of the first page.
  • The homework number
  • The problem number
  • The name and NetID of every group member.
  If you are typesetting your solutions with LaTeX, you are welcome to use our solution template.
• If you discover that you did not receive credit for your group's homework submission, please ask someone in your group to submit a regrade request. We will use the information at the top of the first page to verify that you are a member of that homework group.

Form: How to write

Please make it easy for the graders to figure out what you mean in the short time they have to grade your solution. If your solutions are difficult to read or understand, you will lose points.

Be Honest

• Write everything in your own words, and properly cite every outside source you use. We strongly encourage you to use any outside source at your disposal, provided you use your sources properly and give them proper credit. If you get an idea from an outside source, citing that source will not lower your grade. Failing to properly cite an outside source—thereby taking credit for ideas that are not your own—is plagiarism.

  The only sources that you are not required to cite are the official course materials (lectures, lecture notes, homework solutions, and exam solutions from this semester) and sources for prerequisite material (which we assume you already know).

• List everyone you worked with on each homework problem. Again, we strongly encourage you to work together, but you must give everyone proper credit. If you work in a group of 20 students, then all 20 names should appear on your homework solution. If someone was particularly helpful, describe their contribution. Be generous; if you're not sure whether someone should be included in your list of collaborators, include them. For discussions in large groups, where collecting individual names is impractical, it's okay to write something like "discussions in lab" or "Thursday homework party".
• Include transcripts of all LLM usage. You are welcome to consult generative-AI chatbots to help solve homework problems, just like any other source. But if you use an LLM for any reason, you must include them in your list of sources (just like any other source), and you must include a complete transcript of your conversation, including all prompts and responses, as an appendix to your homework submission.
• If your list of sources and collaborators for any homework problem is empty, write ”Sources and collaborators: None” or something equivalent.
• Please see our academic integrity policy for more details.

Be Clear

• Write legibly. You will lose points if the graders find your work difficult to read. Writing legibly also helps you think more clearly.
  • We strongly recommend typesetting your homework, especially if you have sloppy handwriting. We recommend using LaTeX, but you are welcome to use whatever program and/or markup language you like. A LaTeX homework template is avialable.
  • You are welcome to submit scans of hand-written homework solutions, provided they are clear and easy to read. Write with black ink (not pencil) on white unlined paper (not notebook or graph paper), and use a scanning app to create a high-quality PDF.
  • The graders have complete discretion to decide whether a submission is difficult to read. In borderline cases, the graders will first give a warning, asking the student for specific improvements in future homework submissions, rather than immediately deducting points. Please take this feedback seriously.
• Write sensibly. You will lose points for poor spelling, grammar, punctuation, arithmetic, algebra, logic, and so on. This rule is especially important for students whose first language is not English.
• Write carefully. We can only grade what you actually write, not what you mean. We cannot read your mind, and we will not insult you by trying. If your answer is ambiguous, the graders are explicitly instructed to choose an interpretation that makes it wrong.
• Don't submit your first draft. Revise, revise, revise. First figure out the solution, then think about the right way to present it, and only then start writing what you plan to submit. See also "write legibly".
• State your assumptions. If a problem statement is ambiguous, explicitly state any additional assumptions that your solution requires. (Please also ask for clarification in class, in office hours, or on Ed Discussion, or on Discord!) For example, if the performance of your algorithm depends on how the input is represented, tell us exactly what representation you require. Yes, even if the assumption is “obvious”.
• Don't submit code. Describe your algorithms using clean, human-readable pseudocode. Your description should allow a competent programmer to directly implement your algorithm, in their favorite language, using a software library containing implementations of every algorithm we’ve seen in class, without knowing what problem you're trying to solve. Oh, and they think your favorite programming language sucks.

Be Concise

• Keep it short. Every homework problem can be answered completely in at most two typeset pages or five handwritten pages; most problems require considerably less. Yes, I am aware of the crushing irony.
• Omit irrelevant details. Don't write "AVL tree" when you mean "balanced binary tree" or "dictionary". Don't write "depth-first search" when you mean "whatever-first search". Don't submit code; we want to see your ideas, not syntactic sugar. If your solution requires more than two typeset pages, you are probably including too many irrelevant details.
• Don't regurgitate. Don't explain binary search; just write "binary search". Don't write the pseudocode for Dijkstra's algorithm; just write "Dijkstra's algorithm". If the solution appears on page 374 of Jeff's book, just write "See page 374 of the textbook." If your answer is similar to something we've seen in class, just say so and (carefully!) describe your changes. You will lose points for vomiting, especially if you get the details wrong.
• Don't bullshit. You will not get partial credit for word salad that happens to include some correct keywords.

Content: What to write

• Answer the right question. No matter how clear and polished your solution is, it's worthless if it doesn't answer the question we asked. Make sure you understand the question before you start thinking about how to answer it. If something is unclear, ask for clarification! This is especially important on exams.
• By default, if a homework or exam problem asks you to describe an algorithm, you need to do several things to get full credit:
  • Describe the problem that your algorithm is supposed to solve. This is often the hardest part of designing an algorithm. See the second Deadly Sin.
  • Give a concise pseudocode description of your algorithm. Don't regurgitate, and don't turn in code!
  • Describe a correct algorithm.
  • Justify the correctness of your algorithm. You must provide a brief justification for your solutions, as evidence that you understand why they are correct. Unless we explicitly say otherwise, we generally do not want a complete proof of correctness (because complete proofs would be too long, tedious, and unenlightening) but rather a high-level sketch of the major steps in the proof. Correctness arguments are required on exams only when we specifically ask for them.
  • Analyze your algorithm's worst-case running time. This may be as simple as saying "There are two nested loops from 1 to n, so the running time is O(n²)." Or it may require setting up and solving a recurrence, in which case you'll also have to justify your solution. We only care about worst-case running time. Unless we specifically ask otherwise, you do not have to analyze space.
  • Describe the fastest correct algorithm you can, even if the problem does not include the words "fast" or "efficient". Faster algorithms are worth more points; brute force is usually not worth much. We usually won't tell you what time bound to shoot for; that's part of what you're trying to learn. However, if your algorithm is incorrect, you won't get any points, no matter how fast it is!

    For each problem we assign, we have a target running time in mind. Correct algorithms that meet the target running time are worth full credit. Slower algorithms are worth significant partial credit. We typically deduct 2 or 3 points out of 10 for each extra factor of n in the running time; however, every correct and clearly presented algorithm, no matter how slow, is worth partial credit. On the other hand, algorithms that are faster than the target time bound are worth extra credit; again, we typically award 2 or 3 points for each factor of n. We usually do not give the target running time in the problem statement, because when we do, a lot more students submit incorrect algorithms with the correct running time. First make it work; then make it faster.

  Some problems may deviate from these default requirements. For example, we may ask you for an algorithm that uses a particular approach, even though another approach may be more efficient. (Answer the right question!)