Monday, December 24, 2018

A ♪ ♪ ♪ week

Codeforces Round 513 started the first October week (problems, results, top 5 on the left). The right strategy this time was to skip problem G which ended up not being solved at all and go for problem H, and of those able to execute said strategy scott_wu was the fastest. Congratulations on the victory!

IPSC 2018 took place on Saturday (problems, results, top 5 on the left, analysis). The competition at the top was pretty tough, but in the end team ♪ ♪ ♪ emerged with a four-point lead. Congratulations on a very convincing win!

Problem E2, which I was super disappointed not to be able to solve during the contest, required some basic number theory skills and most importantly a good understanding of statistics: you are given a prime number p up to 10100, a number k, and n<=100 triples of numbers ai, bi, mi. Your goal is to count how many numbers x between 0 and p-1 satisfy the equation ((ai * xbi) mod p) mod mi = ((ai * k + bi) mod p) mod mi for at least one i. Moreover, you need just the approximate count: an error of up to 1% is fine. There are 100 testcases to solve, and the duration of the contest is 5 hours :)

Codeforces Lyft Level 5 Challenge Elimination Round wrapped up the week on Sunday (problems, results, top 5 on the left, analysis). No skipping of problems was required this time, just solve all problems and you're at the top of the scoreboard :) Only tourist and V--o_o--V were able to execute on this simple strategy, and claimed the first two places. Well done!

Thanks for reading, and check back for more!

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