shit

Auto comment: topic has been updated by MillionDays (previous revision, new revision, compare).

For me the greatest problems were :

1762D - GCD Queries

1733D2 - Zero-One (Hard Version)

And those problems were nice and I enjoyed solving them although they are a bit easy:

1697D - Guess The String

1772F - Copy of a Copy of a Copy

1713D - Tournament Countdown

I'd like to select a series of problems, you can see them below:

ConstructOR It's so amazing when I first met with it, due to its brief but beautiful statement and interesting methods (such as exgcd I used in the contest).

Carry Bit In my opinion, It's an interesting problem with some typical but natural methods. What strong feelings I've got when I realized to split the whole 01 array into some parts and enumerate them one by one! (though didn't solve during contest /ll)

Factorial Divisibility It's maybe kind of easy for some of you, but to be honest I haven't solved it during the whole contest, I tried some strange approaches, but the brief tutorial astonished me again ---- You just need to scan from small numbers to the large ones, and contribute i to i+1!

It's my pleasure to share some of my attitudes, and I'm happy to write more about the "best problems" what I thought to be if I have enough spare time.

Some recent ones, off the top of my head:

• 1717E - Madoka and The Best University

• 1486F - Pairs of Paths

• 1499F - Diameter Cuts

• 1443E - Long Permutation

• 1657E - Star MST

Can't solve, but seem cool:

• 1270G - Subset with Zero Sum

• 1726E - Almost Perfect