The TCO Marathon Man

How did you learn about Topcoder in general and Marathons in particular?

One fall’s day in 2006, when I was in a computer room in my university, I heard from my friend(who is working in Microsoft now) about Google Code Jam, which was operated using Topcoder platform at that time. So I learned about Topcoder and tried to do some practice, and started to participate in SRMs. It was really fun because I didn’t have similar experience before, and I was quickly attracted by the contests.

I like optimization problems and real-life problems. When Hanaban introduced Marathon Match in a Korean programming contest community site, I tried to participate eagerly, but failed in first two competitions due to lack of ability and experience. After that, problem Permute was solvable using my limited knowledge of SA. I began to have real interest since then.

Were you dragged into Marathon-style competing immediately?

I had difficult time to solve non-SA problems particularly – probably due to my tendency of seeking optimial solution. And I failed in 2008 MM Round 2/2009 MM Round 1. It was NASA Experimental MM, problem SpaceMedkit which opened my eyes. I spent a lot of time analyzing the given dataset, but my real solution wasn’t that relevant to that analysis. For last two or three days, I started to use some naive automated testing using batch file and it allowed quick development. After the match, I saw chokudai‘s spreadsheet. It had all local testing result from his methods. It struck my head immediately and seemed to light my way forward – I’m still using this methodology when doing every MM. All of these events gave me good experience, especially the last one.

Do you take part in other Topcoder tracks? What about non-TC programming competitions?

I don’t particiate in other tracks – I don’t think I’m really fit.

I used to enjoy CodeForces, but not these days because I’m practicing in the Topcoder Arena for Algo track when I have free time – I think I’ll participate more actively there after TCO finals.

I also participate in IPSC every year as “Andromeda Express” with JongMan and Astein.

How do you organize the process of working on the problem?

I start from naive solution and try to improve from there. If I hit some wall high, I try to think other methods. During the iterative improvements, I should have acquired ‘feeling’ about the problem, and usually it leads to fundamentally advanced solutions.

I think this process gives fairly good result given enough time, but these days I was giving more time to “thought experiments”, thinking about the experience of last year’s 24-hour Final.

What is your favorite Marathon problem of all times? Why?

QualityPolygons was the best. Other Finalists gave good reasons about it, and I fully agree with them.

What is the problem you liked least of all? Why?

I don’t like problems with too much, sometimes not that useful, specification. I just don’t participate contests with that kind of problems, since it’s hard to write naive solution for them.

If you could change one thing about the Marathon track, what would it be?

Increasing the prize money for some amount and the number of prize receivers to 10.

Sometimes problems for money matches seem much worthy than given prize money. Also, giving the money to many people will increase participation. Some of them will emerge with really creative solutions!

Your version of Two Things about Marathon matches?

• Read the problem and submit null solution only with given class definition.

• Do everything to retain rating.

Your most memorable moment of online part of TCO11?

I was briefly first place, around three hours in day 5 or 6 of MM round 3. That was unique experience and gave some confidence to me.
But my most memorable moment was just after systest of Algo round 5 – I had been eliminated in the last round, for three times in last four years.

Your most memorable moment of your overall Marathon participation?

I wasn’t certain about my position after last year’s MM round 3, since there was considerable uncertainty about the preliminary result. Partly out of anxiety and partly out of curiosity, I grabbed solutions of Top 20 and did local testing. After the testing I relaxed somewhat.

How much time you’ve spent on TCO problems?

R1: 4-5 days R2: 1 week R3: 2 weeks.

What does your family think about TCO?

They have good impression, probably because of free flight ticket. My sister is going to fly with me this year

What kind of a problem you’d like to see in the finals?

Problem which is easy to understand but allows a variety of approaches.

Do you do anything to prepare to the finals?

I plan to practice problems presented in Finals. But I don’t think they’re really helpful. It’s more important to have good condition before the contest.

Thanks, and good luck in the finals!