If you want to improve English - highly recommended for reading:

https://nammemememe.substack.com/p/london-is-the-capital-of-great-britain

Daily (183 day streak)

Again, amazing easy problem for binary tree, definitely not a nonsense, go and collect your coins.

https://leetcode.com/problems/balanced-binary-tree/description/?envType=daily-question&envId=2026-02-08

#leetcode #medium

It is already 1 year since I decided to leave Microsoft and started preparing for interviews. Cannot believe I would ever be solving Leetcode FOR ONE FUCKING YEAR.

Now I just need 190 days to get leetcode cap, and then I will stop doing nonsense/bullshit daily problems, only good ones

Today 'm dropping Ticket master system design

Vibe construction workers???
https://www.youtube.com/shorts/wT1WGtQ4Lp4

Yeah, there will be no replacement. Yes, this shit can write code instead of you, research instead of you, BUT, companies are going to pay you for:
1. Validation of its nonsense
2. Taking responsibility. Cause you cannot motivate or punish gpt, but hell yea you can do that to human being

Promised - done:

https://andreyka26.com/ticketmaster-system-design-with-microsoft-engineer

#systemdesign

AHAHAHAHAHAH

okay, not today, but tomorrow 100050000% we are replaced, just tomorrow (parodying the CEO of an AI company)

Daily (184 day streak)

Amazing problem, you can do it easily O(n) space (check hints) or try hard with one algo. But eventually some good problem for DSU understanding and operating. Btw balancing of the trees is basically used most of the database indices.

https://leetcode.com/problems/balance-a-binary-search-tree/description/?envType=daily-question&envId=2026-02-09

#daily #medium

Omg, amazing milestone. Thank you all for being with me. Hope it is useful and sometimes fun for you.
You are giving me motivation to continue.

One q, about networks.
If you have private network and you deployed there your app. App is generally sends GET requests to google.com

Assume there is no firewall at google side, as well as no firewall on the machine that forbids external requests.

Answer is no, let me explain you in the next post.
No worries, I also got caught by that. Just for all my 7 years of exp (not that huge, but still) I never thought about IP of the client in terms of TCP/IP stack, however I knew this info.

That's due to at Snow right now we are doing pretty low stuff related to Networking, I guess this is not my first finding XD

Explanation:

Let's recall TCP/IP stack that is used for HTTP request.
We have 4 layers:
- application layer (HTTP). Only has http related data (text)
- transport layer (TCP / UDP). Adds source/destination ports + other stuff for delivery guarantees.
- internet protocol layer (IP) - IMPORTANT! Source IP, Destination IP + other information.
- physical layer (Ethernet/wifi) - bits.


Critical point here, that IP layer needs BOTH source/destination ips.

Why it works, when you just access google.com from the laptop? it is connected to Wifi or Mobile network, and both of them work as NAT (network address translation).

How it works (wifi has public IP assigned by ISP, provider that gives you an internet basically). When you send request to google.com wifi intercepts your private ip 192.168.X.X and translates to assigned dynamic IP). Google receives your wifi's dynamically assigned IP. The response later is translated back to your private ip on router lvl

#network

Short answer, without NAT - you cannot receive the response, cause your Source IP in IP packet will have your private address which will be discarded by router completely. Even if not -> then router won't know which private ip in iptable is yours to send the response back

At some point I was listening to one presentation, where in case you have multiple servers with deployed apps with public Ips (let's say you pay for public ip in cloud provider) each -> you can save money by putting them to private network.
Then you can use single NAT for external HTTP traffic thus paying only for single public ip on NAT, but not on the servers.

Then I was like: wait a moment, why you need NAT, what is NAT? why can't you just MAKE the requests?? And then I recalled tcp/ip stack, and got the idea by googling it a bit deeper

Daily (185 day streak)

Not sure if it is medium, because brutoforce works.

https://leetcode.com/problems/longest-balanced-subarray-i/description/?envType=daily-question&envId=2026-02-10

#daily #medium

I had interview for Production Engineer in Meta half a year ago.
One of the most intriguing and interesting interviews: Troubleshooting.

You are getting some “situation”. E.g. “at 2AM webservice stopped responding. Just timeouts. You are given ssh access and need to find out a root cause, fix, and perform preventive actions.

The interview process is the following:
You are telling an interviewer linux command - he gives you an output from that.

All my life I was deploying to VMs using docker ofc, it was never a raw process.
So my first statement was: “I am running docker ps”

He tells me: “docker is not recognised as a command”