Rejected by a company because the "Staff Engineer" wanted me to prove Inverse Ackermann on the spot lmao
Need to get this off my chest because the ego tripping in tech interviews is honestly insane right now.
Had an interview earlier this week with a tech firm in Dubai for an SDE-2 role. 45 min round, 2 DSA questions.
First question was an easy-medium, wrapped it up and dry ran it in like 10 mins. Clean code, optimal TC/SC, zero hiccups.
Then he gives me Q2 which was a union find problem.
I told him I’ll use DSU with path compression and union by rank, and casually said the time complexity per operation is basically constant time amortized.
This guy (who was a staff engineer btw) legit paused, looked confused, and went: "Wait, how can it be O(1)?"
I explained that it's amortized O(α(n)) where α is the inverse Ackermann function, which never crosses 4 or 5 for any practical value of n, so it's treated as effectively constant.
Bro literally frowned, shook his head, and hit me with:
"No that doesn't sound right, can you explain the mathematical proof?"
I told him politely that I haven't studied the proof, and that such a mathematical proof is obviously way beyond the scope of an SDE interview, but it's a standard established result for DSU.
He got visibly pissed off and went cold after that and asked me to write the code.
I still kept my cool, coded up the whole solution properly with find/union, tested it against edge cases, and wrapped up with time to spare.
Woke up today to an update from the recruiter saying that my feedback is "leaning negative".
Imagine failing a candidate because you didn't know basic algorithm complexities and got your ego bruised when called out. Absolute joke of an interview process.