In this course you will learn the techniques and skills needed to solve algorithmic programming contests problems such as those that appear on the ICPC, Codeforces, DMOJ, and AtCoder. Much of your time will be spent writing programs on your own to solve problems.
Some students may go on to participate in the ECNA regional event, the ICPC North America Championship, and possibly even the ICPC World Finals. The ECNA Regional will take place on Sunday October 29th in Youngstown Ohio.
But the skills you will pick up from the course are far more valuable than just enabling you to win contests. Many of the algorithms and techniques are classic ones that every computer scientist should know. You will also learn to think about algorithms in a deeper way, because many of the problems require you have to devise a new algorithm, not just apply a classic one. You will also become highly fluent in a programming language of your choice. These skills will be of great value in your other classes, in your job interviews, and in your future work, not to mention the satisfaction you will get from solving these problems.
Basic Information
Weekly Problems
Rules and Academic Integrity
Grading
Logistics
Training Resources
Learning Material Diversity, Equity and Inclusion
The regular weekly contests will take place Wednesdays beginning at 7pm in Posner Hall 151, and last 2.5 hours (you don't have to stay the whole time.) Occasional lectures may take place at 6pm in the same room. They will be announced on Discord. Lectures will cover introductory content aimed at beginners to competitive programming. Although attendance to the lectures is optional, it is strongly encouraged for beginners. During the contests, the instructors will be available for help in the classroom, or via Discord.
- Instructors: * Danny Sleator <sleator@cs.cmu.edu> * Li Chen <lichenntu@gmail.com>
- Class Meetings: Wednesdays from 7:00 to 9:30, Posner Hall 151
- Discord server: join link
- Codeforces 15-295 Group (REQUIRED: Join This Group!)
- Name List (REQUIRED: Add Your Info!)
- Grade Spreadsheet: TODO: Not Set Up yet
For more information on how to join these groups, etc, see the Logistics section below.
Contest Link: Here
Solutions: For Editing (TODO) For Viewing (TODO)
Contest Link: Here
Solutions: For Editing For Viewing
This week, we will explore even more graph algorithms. In particular, we will be looking at applications of maximum network flow.
Lecture: Video
Lecture Notes: Basic Algorithms Advanced Algorithms Min-Cost-Flows
Implementations: Max Flow (C++) Max Flow (Python)
Contest Link: Here
Solutions: For Editing For Viewing
Geometry! Love it or hate it! Geometry problems are often some of the most difficult problems that appear in programming competitions because they can be full of corner cases, precision, and rounding issues. This week, we will practice the fundamental techniques behind solving geometry problems.
Tutorial: Geometry tutorial
Contest Link: Here
Solutions: For Editing For Viewing
This week we will cover some advanced data structures that you won't find in your language's standard library. We'll learn about dynamic ranged minimum queries over arrays.
Lecture: Slides
Resources: A poem in honor of SegTrees by Chat GPT 4
Contest Link: Here
Solutions: (no solutions document was created)
This week we will learn how to count things!
Tutorial: Counting tutorial
Contest Link: Here
Solutions: For Editing For Viewing
Contest Link: Here
Solutions: For Editing For Viewing
This week, we will continue the theme of graph algorithms and talk about shortest path problems in graphs. The fundamental algorithms that you will need to learn to solve these kinds of problems are breadth-first search (mentioned last time) and Dijkstra's algorithm. Other algorithms, such as Bellman-Ford and Floyd-Warshall are also very useful.
Lecture: Slides
Resources: Lecture notes on Bellman-Ford and Floyd-Warshall
Contest Link: Here
Solutions: For Editing For Viewing
This week we will talk about graph algorithms. This is a topic that will probably span multiple weeks as we cover things like shortest paths, minimum spanning trees, and network flows. For this week, we will focus on the fundamentals, and cover things like how to represent graphs and how to implement graph traversal algorithms (breadth first search and depth first search).
Lecture: Slides DFS code in C++ BFS code in C++
Resources: Lecture notes on DFS and Strong Components
Contest Link: Here
Solutions: For Editing For Viewing
This week, we will practice the use of dynamic programming (DP) as a technique to solve programming competition problems. DP is quite possibly the most frequently occuring algorithmic technique used in competitions, with every ICPC contest always featuring at least one, if not several problems that require it. Mastering this technique is key to becoming a strong competitive programmer. DP revolves around two key concepts, optimal substructure, which means that a problem can be solved by breaking it into smaller versions of itself (much in the same way as divide and conquer), and memoization of overlapping subproblems, which means to cache the solutions to the smaller problems in case they need to be solved multiple times. Of all topics in competitive programming, it probably requires the most practice in order to master, so get started!
Lecture Slide: Here
Resources: 451 Notes 1 451 Notes 2 Contest Link: Here
Solutions: For Editing For Viewing
This week, we will solve problems that use the binary search technique. You might think of binary search as an algorithm for finding an element in a sorted list, but it is actually a much more general technique than that, and can be used to solve a wide range of problems. Essentially, binary search allows you to solve problems where you must minimize or maximize some quantity subject to some contraint, as long as that constraint is monotone. A constraint is monotone if it is false for all values of x up to some value, and then becomes true after that value. Binary search allows us to efficiently find this partition point, and hence solve the corresponding optimization problem. The practice problems this week should help you to learn to apply this powerfull technique.
Lecture Slide: Here binary search code ternary search code
Contest Link: Here
Solutions: For Editing For Viewing
This week, we will focus on the most commonly used and fundamental algorithms and data structures in competitive programming. We will review and practice using arrays, binary search trees, hashtables, and priority queues. Knowing and understanding how to use these data structures in your favourite programming language is crucial to being able to quickly implement solutions to problems. We will mainly use C++ to demonstrate, but the ideas should be applicable to any language that supports these data structures.
Lecture Slide: Here
Contest Link: Here
Solutions: For Editing For Viewing
This week has no particular algorithmic theme. Instead, we will go over the basics of competitive programming and do our first contest on Codeforces. Please make sure you have a Codeforces account ready to go and understand how to upload your solutions to the problems. You should do some practice problems to get the hang of writing and submitting solutions to the Codeforces system.
If you don't know how to read from standard input and write to standard output, here's a tutorial showing how to do it.
Contest Link: Here
Solutions: For editing For viewing
You can make use of generic on-line resources while solving problems. These include things like language documentation, API documentation, algorithm descriptions, terminology, etc. You are allowed to use any code you have written, at any time in the past, for any purpose. However, you should not search for or make use of code written by others to solve the specific assigned problem. You're allowed to copy somewhat standard pieces of code (e.g. a primality test) that you find on-line or in a book.
So to summarize, each student should write his or her own code. If you're stuck on a problem, you are welcome to discuss it with another student in the class, or the course staff. But you cannot copy another student's code.
The violations described above are regarded as an academic integrity violation, and -- depending on the severity -- will result in penalties and/or be reported to the appropriate university authorities.
This course is 5 units. Each week you will be given several problems to try to solve during class. You will be allowed (for half credit) to solve these problems during the week after the contest ends. You can also get credit for solving problems during rated contests on Codeforces. (This site run rated contests approximately every two weeks.)
To be more specific, you can earn points from the following sources:
The differences between 15-195 and 15-295 are: Students enrolled in 15-295 will not get credit for problems A and B of the weekly contests, but 15-195 students can. A student can take 15-195 only once, but 15-295 can be taken repeatedly.
Here is how your grade is determined:
score ≥ 25: A
score ≥ 15: B
score ≥ 10: C
score ≥ 5: D
Everyone in the class and/or on any programming team should be in this Discord workspace. This is one way we communicate with the class. Here is the join link.
Everybody in the class is required to have a Codeforces account. We will be running our weekly contests on the Codeforces website via a mechanism called "mashups". If you do not already have an account on Codeforces, please create one.
Add your name along with your Codeforces handle name and other information to this spreadsheet. (It's the same one in Basic Information list above.)
To join the 15-295 codeforces group, first create your codeforces account, and login to it. Then go to this 15-295 Codeforces Group page. On this page you should see a list of the contests created for this course. Now, toward the right side of the page click on the link to join the group. (You only have to join once.) Then a "Register" link should appear next to the contest. Click on this link to register for the contest. After that another "Enter" link should be available for you to join the contest (if it has already started).
As we proceed through the semester we will tabulate your results and put them into this NOT SET UP YET document.
First of all if you need help reading from standard input, or writing to standard output, see this link.
There are many online resources available for you to train with if you intend to become a serious competitive programmer. You can find thousands of practice problems for you practice and improve your skills. Some good places to find practice problems include:
If you are a beginner looking for resources to learn the various topics that appear in typical contests, some good sources are:
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