### stdfloat's blog

By stdfloat, 3 weeks ago,

UPD: I suppose no. Thanks lrvideckis for explaining my mistake in this comment.

I think PQ takes too much memory because of what happened in CF Round 923.

In this contest, because of I couldn't solve E, I read F, after some time I found solution. In the end of my solution, I have to find any path from $mn.ss.ss$ to $mn.ss.ff$ which doesn't contain a node more than one time, in this code I used dijikstra for it(I don't know why I didn't use bfs). And it used more than 256 megabytes.

Today, I used bfs instead of dijikstra in this code, and I suprised, it took only 43 megabytes. In time 2, in memory 6 times smaller than previous code. I'm sad about I didn't use bfs in contest, but I'm happy about I learned a lesson.

Did you have any experience like these?

• +14

By stdfloat, 5 weeks ago,

I have a request for everyone reading this blog: please post a comment sharing what you do/did for training for IOI (or perhaps for other OIs). I'm primarily interested in hearing what you actually do/did, not what you would recommend to someone else who's training for IOI (though if you want to give advice, please feel free to do so).

It'd be good if you answer those questions

If a blog similar to this already posted, sorry for reposting, could you give the link of it?

• +40

By stdfloat, 5 months ago,

I was trying to solve IZHO14_bank on oj.uz. In problem $n, m <= 20$ and Time Limit is 1s.

Time complexity of my solution is $O(2^m \cdot m \cdot n)$. It's $TLE$ because $2^{20} \cdot 20 \cdot 20 = 419 430 400 > 10^8$.

My both code have same time complexity but my $1^{st}$ code is $TLE$, $2^{nd}$ got $100$ score.

Can someone explain why my $2^{nd}$ code isn't $TLE$ $?$
$1^{st}$ submission https://oj.uz/submission/854216 gives $TLE$,
$2^{nd}$ submission https://oj.uz/submission/854864 got $100$ score.

• +13

By stdfloat, 5 months ago,

6 months ago, I posted a blog hoping to find OI groups on CF since most sites are blocked in my country. Unfortunately, I couldn't find.

In CF blogs, for practicing to OIs, suggested is solving easier OIs. But I have only CF with 2017-2023 IZHO, 2002-2023 IOI, and some from gym. I can get some points on IZHO, but I can't solve full & IOI is hard for me.

It'd be good if you answer those questions
cf, prep, izho, ioi, oi,
• +30

By stdfloat, 7 months ago,

In my country many sites are blocked.

Such as

Luckily Codeforces isn't blocked in my country, and I'm looking for OI groups on CF.

If you know such groups please comment it. It will be very helpful.

Unfortunately I can't use vpn
• +49