Episode 39 - String Concatenation

This week's episode of Algorithms Live! features David Harmeyer (SecondThread). In this episode, we discuss his problem String Concatenation from Facebook Hacker Cup 2021 Round 2. We recorded the video over the weekend and will be premiering the video on YouTube this week. During the premier both David and I will be available on the chat to answer any questions.

See you there!

Episode 37 - Venture Cup

This week's episode of Algorithms Live! features the return of scott_wu. In the episode we discuss his involvement in Venture Cup, the interest of venture capitalists and tech companies in competitive programming, his work as a commentator for this year's Topcoder Open, the relationship of esports to competitive programming, and the problem 626F - Group Projects from the first Venture Cup. Most of the episode is podcast style, so I've included time links in advance to make it is easier to navigate to parts of the discussion that interest you. :)

The episode is available at this link. Enjoy!

Episode 36 - El Toll Caves

This week's episode features Mikhail Tikhomirov (Endagorion). You may know Mikhail from his many problems in Codeforces or other online judges. He has been a finalist of TCO and Google Code Jam and helped host the Barcelona Programming Bootcamp. Mikhail is an ICPC coach for Moscow Institute of Physics & Technology. His teams have earned two gold medals and a silver medal at ACM ICPC World Finals in the past few years. He also has a YouTube channel where he regularly post screencasts.

In this episode we will be discussing his problem El Toll Caves from the Barcelona Bootcamp. This is a math intensive problem with close relationship to the Euclidean algorithm.

If you have any questions for Mikhail, please leave comments on this post with the question or ask the question live during the stream.

See you live! (episode)

Episode 35 - Looking for a Challenge?

This week's episode features Tomasz Idziaszek as a special guest. Tomasz was an ICPC World Finalist from 2005 and a TCO Finalist from 2004-2005. He is an author of over 100 problems, including many hard and interesting problems from Algorithmic Engagements. He was an editor for the polish educational magazine Delta and the famous competitive programming book "Looking for a Challenge?". In 2018 he was a problem setter for the IOI. He also maintains the website http://www.algonotes.com/ that offers interesting educational materials on advanced algorithms.

In this episode we discuss the history behind "Looking for a Challenge?" and his famous problem Termites, which was included in the book. This problem is truly beautiful and I hope many of you will enjoy the episode.

Update: Anyone interested in the getting a copy of the Looking for a Challenge book can find information in this blog post. You can also solve the recommended Woodworms task by seeing the problem statement at this link and on an online judge in this link.

Episode 34 - Educational Streaming w/ Errichto

This week's episode will feature Errichto and will take place on Sunday, December 16th. If you are interested in viewing the live stream, you can find the link here or view the video after the stream following the same link.

Many of you know Errichto as a prolific problem writer and his recent appearances in TCO, Google Code Jam, Facebook Hacker Cup, and many other programming contest finals. He represented the University of Warsaw in the 2018 ACM ICPC World Finals, where his team placed 14th. This year he started an educational stream for competitive programming that is growing in popularity.

In this episode, we will discuss the benefits of educational streaming in competitive programming and ideas for making competitive programming more popular. Topics will include: how programming contests relate to e-sports, broadcasts for programming competition finals and how they can be improved, and algorithms videos on YouTube and what we would like to see in the future for popularizing the sport. I think this will be a fun podcast style stream. Please ask questions on this post for ideas that you would like to see discussed.

As with all Algorithms Live! episodes, we will be discussing an interesting algorithmic programming challenge. In this episode, we will discuss Errichto's problem Disjoint Triangles. As build up to this problem, we will also be discussing Interstellar Battle from Bubble Cup earlier this year. This is sure to be an exciting episode with many interesting topics and ideas.

See you live!

Episode 33 - Maximum Flow Intuition

During September I attended the IOI as the USA team's deputy leader. The event was lots of fun and I met many new friends, some of which will be future episode guests. While attending I also presented my paper on Tidal Flow, an algorithm I invented while training for ICPC contests. The paper also served as an extensive study on maximum flow algorithms. During testing I implemented many new flow algorithms and decided it would be fun to share some of these algorithms in an extended flow series.

The first episode of this series is now available here. I'll be going over terminology, proofs, algorithms, and patterns as the series expands. There is much to talk about. I'll be interspersing the episodes with some guest episodes I've been planning. Hopefully this variety will keep the episodes exciting for all viewers.

In other news, I've received many requests to start a GitHub repository to store all of the code I write during episodes. Such a repository is now available here.

Episode 32 - Fracturing Search

It has been several months since I've created an episode of Algorithms Live! but I'm excited to restart the show. I'll be making some changes to the format of the show that I'm hoping some of you will really like. Before I get into all of that I want to share some personal updates and explain what I've been doing the past few months.

Sadly, things did not work out with drive.ai. I enjoyed the experience, met many interesting people, and learned a great many things. Not working while in the bay area is terrifying so I had to dedicate most of my time figuring out how to leave the bay area and setting up my next life steps.

During the last few months, I worked on making videos for Interview Kickstart. This has been interesting because I started to think about how I could change the format of Algorithms Live! so that it is more useful using some of the ideas from making IK videos. One difficulty in running the show is finding a guaranteed quiet place to schedule a live episode. When I originally ran the show, I would run the episodes late at night in my office at UCF. Not having a dedicated quiet office has hurt running the show live. So I've decided to run more polished pre-recorded episodes as an experiment. Let me know what you think of the new format!

So now on to more exciting and fun news. The first is I'll be attending the IOI this year as USA's deputy leader. So if you are attending IOI, please say hi! I'll also be presenting a paper on Tidal Flow this year at the IOI Conference (journal, paper). Tidal Flow is a maximum flow algorithm I invented while training for the ICPC World Finals in 2012. My team wanted an iterative fast flow algorithm that was also easy to implement and understand. The result was the Tidal Flow algorithm. I taught this technique, along with many other fast flow algorithms, while training teams at UCF for many years and the algorithm enjoyed popular usage among our teams. If you decide to read the paper or use the algorithm, I'd be interested to know what you think of it.

Earlier this summer, I helped coach at the USACO training camp. One problem I set during the camp was an enumeration problem. The problem is given a weighted graph, print the cost of the kth smallest spanning tree (where n <= 50, m <= (n choose 2), k <= 10,000). Give this problem a try. Can you get something that runs efficiently on random, fully connected graphs? After the contest I presented the concept of fracturing search as a method for solving this type of enumeration problem. The technique is generally applicable, and many of the USACO finalists found it interesting. The idea is based off Murty's assignment ranking algorithm (paper, altlink). There is even an paper that solve this same problem using the technique (paper). So I've decided to turn this technique and problem into an episode. I hope you enjoy the idea as much as I do.

So here is episode 32 (episode). I'd love to hear thoughts of the episode and the new format. Is this format better? What should be changed? I have many more episodes planned and will be releasing them regularly following this year's IOI.