Daily 347 day streak

(yesterday)
Extremely hard segment tree / sparse tree problem. Hedge funds shit, don't recommend, and didn't do on my own.

https://leetcode.com/problems/maximize-active-section-with-trade-ii/?envType=daily-question&envId=2026-07-23

#daily #hard #pattern

Daily 348 day streak

This is not bad problem for learning bitwise operations and having mental model about XOR.

https://leetcode.com/problems/number-of-unique-xor-triplets-i/?envType=daily-question&envId=2026-07-23

#daily #medium #pattern

I owe you now 2 hard problems from the list. Weekend it will be done folks. We don't skip any single one. If problem is bullshit -> we just do other normal problem of the same level

These days I'm working like 10 hours a day. At some point maybe I will have extremely good proof that making project AI first, zero code written, all PRs opened by AI might not be the best idea if the project is somewhat more complicated than crud.

There are bunch of other problems, so I cannot explicitly blame AI, but it definitely has contributed. It makes me feel much better about job security

Another thing: weekend - Concurrency article is going to be dropped (potentially even, tomorrow, Friday). I have only Mongo left to cover, for now Postgres and Redis is covered precisely down to source code.
Whenever you would have some hot discussion about concurrency - you will be able to throw ref from article to the face of opponent and leave the discussion as winner❤️

Say which command you use the most in your life without actually saying that. I can type these 3 with closed eyes being sleeping and unconscious with speed of light

Daily 349 day streak

Actually this is easier IMO than yesterday's problem, if you would build the same intuition. However no pattern here. So I wouldn't recommend solving it.

https://leetcode.com/problems/number-of-unique-xor-triplets-ii/description/?envType=daily-question&envId=2026-07-24

#daily #medium #nopattern

Daily 350th day streak

Finally we've got easy problem. I can sleep calmly. Problem for 2 mins coding - go for it. No pattern though

https://leetcode.com/problems/maximum-product-of-two-digits/description/?envType=daily-question&envId=Invalid%20Date

#daily #easy #nopattern

ARE YOU READY?????

FINALLY, I have finished. One note, I'm so-so confident in Postgres and Redis, but I'm not so sure about Mongo, I have researched from the scratch. So in case some of you find a real mistake in explanation/mental model that I'm giving - pls let me know somehow, and if you want -> I will mention you as technical reviewer in the end of the article

this applies to all my articles. My goal is to present people truth, indepth understanding and mental model.

We have got first Technical Reviewer for the article🥳. Kudos to Bohdan, he found nice gaps and misleading parts, thanks!

The more I work in tech the more I understand review - is always a must

I'm very happy and proud that here we have high level people who can do nice technical reviews and know a lot of internal/underhood stuff.

Daily 351st day streak

Easy again, but be careful, this easy WILL NOT accept bruteforce (as typically easy problems do).

No pattern here.

https://leetcode.com/problems/maximum-product-of-three-numbers/?envType=daily-question&envId=2026-07-26

#daily #easy #nopattern

mailchimp - suck my balls. Switched to kit.com -> incredible experience, easy to set up, clear instructions, didn't have to buy email in my DNS provider.

kit -> I recommend
mailchimp -> I don't recommend.

BTW kit didn't pay for that, unfortunately, I wish they did.

Good thing about mailchimp - it allowed me to export all 90+ emails that subscribed to news letter. So now I will be able to run a "hey there is new article - go and check it". Now I'm as annoying as all these blogging platforms.

I just don't know how else to retain folks that got interested in article, but didn't follow telegram or something, because they don't have it.

I'm wondering, how is it useful overall these "email news letters". I have zero subscriptions like that, not sure about that. But better to have than not to have

Hopefully I won't get banned

Daily 352nd day streak

I'm very scared about tomorrow, as today we've got third day in a row with easy Daily question. Pretty trivial one, and again no pattern

https://leetcode.com/problems/maximum-product-of-two-elements-in-an-array/description/?envType=daily-question&envId=2026-07-27

#daily #easy #nopattern

Recently I saw one reel about discipline, and it had quite good insight.

To maintain your discipline and consistency - don’t expect yourself to do daily tasks (reading, leetcode, exercises, whatever) with high energy, performance and quality.

Sometime you do 60-70% of your performance, e.g read 10 pages instead of 30, solve easier problem, but still you did it. This is the way to go. This is what I do as well.

© Andrii, engineer, personal coach, motivator, and clown 🤡😁

Daily 353d day streak

Pretty easy problem I would say, just don't miss one edge case: "inini" -> "inini", not 'niiin'.

No pattern, so skippable.

https://leetcode.com/problems/smallest-palindromic-rearrangement-i/?envType=daily-question&envId=2026-07-28

#daily #medium #nopattern

Are there rust folks? I mean I am working on rust project but I dont understand rust much.

The question: piece of code that I have seen in threads, in any other languages, will lead to lost updates in concurrent environment.

BUT rust has this “mutating borrowing”, and I don’t know the internals and specifics. In theory, if only single thread can mutate state - it should be thread safe by definition. But maybe some experts can correct this statement.