A week of 14

The Jul 23 - Jul 29 week warmed up with Codeforces Round 499 on Thursday (problems, results, top 5 on the left, my screencast, analysis). Without taking the challenges into account the top of the scoreboard would be quite packed, but the challenges are of course taken into account, skyrocketing Kostroma and cki86201 to clear first two places. Well done!

The main event of the week took place on Saturday, with TopCoder Open 2018 Round 4 selecting 14 finalists that would go to Texas (problems, results, top 14 on the left, parallel round results, my screencast, analysis). Both harder problems were approachable, but nobody was able to get all three, resulting in a fairly diverse scoreboard. Kankuro was still considerably faster than everybody else,
and has also cemented his lead with a successful challenge. Congratulations to Vladislav and to everybody who qualified for the onsite round!

I found the medium problem in this round quite educational, if a bit standard. You are given a program for a drawing robot consisting of at most 250000 commands. Each command is either F  "move forward by 1 unit, drawing a line", L "turn left by 90 degrees", or R "turn right by 90 degrees". The drawn polyline splits the plane into multiple regions, some finite, some infinite. Your goal is to return the list of the areas of all finite regions.

Thanks for reading, and check back soon for the solution!