From now on, as they are changing domains the next day after my report - I will be posting domains to report here, so please join me, and let's ban motherfuckers, or at least make them pay for domains. For you it will be few clicks I will leave report content and links

Daily (111 day streak)

Everyone in discussion is keep saying it is hard, but I got stuck in understanding how to understand the node is leaf, or node is root, or node in the middle.
I will give you hint: the node is leaf in graph only in case it has single connection and this connection is parent. Otherwise problem is not that hard (check hints in leetcode)

https://leetcode.com/problems/maximum-number-of-k-divisible-components/description/?envType=daily-question&envId=2025-11-28

#daily #hard

Created an article about this website along with demo how this SharedWorker hides XHR/Socket/etc requests in the Network Tab:

https://andreyka26.com/this-phishing-site-hides-requests-in-network-tab

Daily (112 day streak)

Easy one, Happy Saturday, probably the shortest solution I have ever had.

https://leetcode.com/problems/minimum-operations-to-make-array-sum-divisible-by-k/description/?envType=daily-question&envId=2025-11-29

#daily #easy

Daily (113 day streak)

Actually I would say intuition here to build is pretty hard. But once you have it solution is not that cumbersome or hard

https://leetcode.com/problems/make-sum-divisible-by-p/description/?envType=daily-question&envId=2025-11-30

#daily #medium

Daily (114 day streak)

Hard, and it is hard, especially to build an intuition. But in the comments I will leave the hints that helped me to build mental model

https://leetcode.com/problems/maximum-running-time-of-n-computers/description/?envType=daily-question&envId=2025-12-01

#daily #hard

Daily (115 day streak)

Nice problem. I found out that I really like when leetcode problem has something physical or semi physical. Today it is geometry and trapezoids. However some simple math is used here.


https://leetcode.com/problems/count-number-of-trapezoids-i/description/?envType=daily-question&envId=2025-12-02


#daily #medium

After 1 month of procrastinating and writing in background, it is eventually out. I guess this is the most detailed article about Stripe System Design.

Please leave your thoughts about the decisions made in the design and overall about the article.

https://andreyka26.com/payment-gateway-stripe-system-design-with-microsoft-engineer

For technical articles I think that will be it. We are starting soon writing about leaving Microsoft, about relocation to Ireland, about Snowflake, etc.

You gonna have the link the first ofc

Tomorrow is fun:

Daily (116 day streak)

One of the rare cases, where problem is hard, I didin't solve it on my own, but I really liked it. Hints, geometry and intuition are in the comment section

https://leetcode.com/problems/count-number-of-trapezoids-ii/description/?envType=daily-question&envId=2025-12-03

#daily #hard

As we seen, some math background is needed for the leetcode question above, which was many times asked in Google. So, let's add it as separate posts

How to check that lines are parallel?

1. Calculate vectors out of coordinates
dx = x2 - x1, dy = y2 - y1 => vector = (dx, dy)

2. Calcualte a slope = dy / dx.

3. any two lines that have the same slope (dy/dx) are parallel

#math

How to check that two vectors are collinear (share the same line)

The idea behind is to calculate where both vector would intercept Y axis.
We can do it using line formula y = kx + b. For every single point in all vectors we know x, y, k = dy / dx. From these values we can find b

#math

Daily (117 day streak)

Interesting problem, I wouldn't say it is hard, simulation will work, the trick here to write a good simulation, or figure out smart algo

https://leetcode.com/problems/count-collisions-on-a-road/description/?envType=daily-question&envId=2025-12-04

#daily #medium

Daily (118 day streak)

Happy Friday, enjoy, 3 minutes easy problem

https://leetcode.com/problems/count-partitions-with-even-sum-difference/description/?envType=daily-question&envId=2025-12-05

#daily #easy