Daily 344th day streak

Very good problem, but it was very hard to build intuition about. And also hard to debug personally for me. But it is very good, definitely needs to be done, and has many patterns inside.

https://leetcode.com/problems/smallest-subsequence-of-distinct-characters/description/?envType=daily-question&envId=2026-07-19

#daily #medium #pattern

A bit of content for tomorrow. I had to record (and write an article) as it was planned long time ago, and was asked many times before.

Concurrency article will be ready soon as well.

https://live.andreyka26.com/i-solved-750-leetcode-problems-and-here-what-ive-learnt

Daily 345th day streak

Pretty easy, but required some time for me to do in place.

https://leetcode.com/problems/shift-2d-grid/description/?envType=daily-question&envId=2026-07-20

#daily #easy #nopattern

Comparing to Dubrovnik last year, I spent 100% less money: 0 EUR, or to be precise - I owe dinner to my friend with car for getting me there, which is 20-30 eur😁

Lol my street does not have light😁
Didnt happen to me for past 5 years. I Have vibe like in my home town / village during the storm, there is power outage for the whole night

Vibe 🔉🔉🔉

Cooking folks, it is cooking, next days...

I really want to give single article that will be enough for race conditions problems in 99% of the cases (it will be useful for your daily work as well)

Daily 346th day streak

A bit bullshit problem, I don't see any pattern here to be honest. But not really hard, quite doable.

https://leetcode.com/problems/maximize-active-section-with-trade-i/description/?envType=daily-question&envId=2026-07-21

#daily #medium #nopattern

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.