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### hmehta's blog

By hmehta, history, 8 months ago, ,

Hey All!

Topcoder SRM 760 is scheduled to start at 21:00 UTC -4, June 12, 2019. Registration is now open for the SRM in the Web Arena or Applet and will close 5 minutes before the match begins.

The round is prepared by teja349 and tested by Errichto

This is the third SRM of Stage 4 of TCO19 Algorithm.

Good luck to everyone!

• +30

 » 8 months ago, # |   +2 There's a typo in the title, perhaps you meant SRM 760?
 » 8 months ago, # |   0 Auto comment: topic has been updated by hmehta (previous revision, new revision, compare).
 » 8 months ago, # |   +8 Starts in 5 mins !
 » 8 months ago, # |   +30 Recently I got some time to start doing Topcoder, but I am really surprised to see that there are just about 250 participants in a single round. I heard that there was a time when Topcoder was very popular. Also the problems are nice and require insights. Does anyone know why it becomes not so popular all over time?
 » 8 months ago, # |   0
•  » » 8 months ago, # ^ |   +35 It's a bit like posting a link to a tutorial on flows when a problem requires a flow.
 » 8 months ago, # |   0 How to solve 250 Div 1 ? I've tried but there were a lot of cases and I could not control all of them.
•  » » 8 months ago, # ^ |   +15 The first round has $C(N,N/2)$ ways to choose which teams play home and then $(N/2)!$ ways to match teams with each other. In the second round, home-away teams swap and you need to rearrange away teams so that nobody would play the same match. You need permutations that don't have an element $p_i = i$. This is called dearrangements and there's a recursive formula for that.
•  » » » 8 months ago, # ^ |   0 Thank you a lot ! :D
•  » » » 8 months ago, # ^ |   0 Darn, I didn't pay attention to the "nobody would play the same match". Beautiful problem, very elegant and "could actually happen" in the real world — maybe not with n=500000. :-)