Once long ago when I interviewed at Apple I was asked the classic "fork in the road, two guys, one always tells the truth and one always lies" riddle, with complete earnestness as far as I could tell. Possibly the single worst interview question I've ever been asked.

Of course I told the interviewer I'd heard it before and then gave the correct answer. In my case we just ended up chatting about previous experience instead of doing another brainteaser and I ultimately passed the interview, I think. But afterward the recruiter strung me along for weeks telling me they wanted to make an offer but not giving me one, and I ended up going to Microsoft instead.

Not the worst interview experience I've had, though. That would be the time I interviewed for a full time position after an internship and a group of guys who knew me and had worked with me all summer asked me a pointless brainteaser as the only interview question. I crashed and burned for a full 40 minutes in front of them. Humiliating, and pretty much a pointless hazing ritual as they offered me the job anyway. Luckily I got a better offer and was able to turn them down.

Here are some other brainteasers I've been asked in interviews. I actually think these physics based ones are fun (probably because I had no trouble solving them), but they're still terrible interview questions:

You're in a boat on a lake with a bowling ball. After you drop the ball overboard and it sinks to the bottom, is the lake water level higher or lower or the same?

Three balls are on three downward sloping tracks. One track is a straight line down to the end, the second is the same except for a small hill in the middle, and the third is the same except instead of a hill it has a dip. All tracks start at the same height and end at the same height and cover the same horizontal distance. The balls are released at the same time and roll to the end without leaving their tracks. Which one gets there first?

My favourite interview question that I received was when I was asked to write code that would serialize/deserialize a binary tree and was told it was fine to use "any programming language".

They received a crash course in the power of Haskell ADT and `deriving (Show, Read)`.

Just don't ask brain teasers when you conduct an interview; I believe they give no valid signal at all, and I also believe Microsoft does not ask them anymore.

The coding questions that require an "aha!" moment are very similar to brain teasers, and should also be avoided.

When I conducted interviews for FAANG, I asked somewhat simpler coding questions, something around DFS and/or topological sorting (without calling it by name, of course), because those are thing which you might actually need to implement at work: people sometimes traverse JSONs, and people sometimes resolve dependencies. No one has ever told me "oh, I know this problem, it's DFS", because surely I know they know it. Just show me that you can write the code.

> Microsoft, of all places, might sound like a weird company to target in 2026.

Heh, Microsoft might actually have been weird to target in 2015, especially in SV / startup circles, given that pg had declared it dead in 2007 (https://paulgraham.com/microsoft.html) I guess the Netherlands didn't get that particular memo.

In 2026 Microsoft might actually be interesting again, given it's up there in the Mag 7 jockeying for position in the AI race. I know it's gonna be impossible to get an accurate vibe-check on HN, but I wonder what younger folks think of it today...

Counterpoint to many responses here - when I have interviewed people, it’s a really positive signal if the candidate says they have already seen a problem- the we can move onto something more interesting! Not solving does not mean failure either. As a candidate myself I always mention if I have seen similar problems, such as finding primes - real example, and I was hired on that loop at Microsoft!

On the other hand, if I heard that a candidate had not mentioned they had the same question twice, or later let it be known they already knew the answer, I would lose a lot of trust in them.

Be honest; it’s more likely you will be hired by honest people.

In these circumstances I always say "I've seen something similar before". That has the benefits firstly, that the interviewer will probably go ahead with the question anyway while still noting your honesty; and secondly, that it's usually true - it's possible this problem is subtly but importantly different from the one I'm pattern matching against. There are half a dozen versions of this ball problem.

I really loved to work there. I knew alot of friends, toured the campus, and even worked with prior employees that had good experiences. Every product before 2015 was beautiful (i still miss my Zune).

Then they broke me. I tried to give feedback on the products, interviewed, and really tried to reach out to them. Mostly ignored (except Outlook team, thanks ). The heavy marketing and tech debt within Windows is what did it for me. Rant over.... the interview felt like some trick questions at that time.

> You have 12 marbles and a balance scale. One of the 12 marbles is inconsistent with the others, meaning it could be heavier or lighter than its peers of normal weight. You are allowed to use the balance scale exactly 3 times to identify which of the 12 marbles is irregular AND determine whether it is heavier or lighter than normal.

I also got this riddle, in 2015. I couldn't solve it. Tbh, I think it's a terrible question. There isn't really a step-by-step problem solving process, but you just need to have a "leap" to realize you can weight the marbles in groups of 3. I also got rejected. It's crazy to get rejected from a one-question riddle like this

Odd that they received a brain teaser at a MS interview in 2015. IIRC that's several years after internal interviewer training was updated to recommend that brain teasers not be used in interviews because they weren't useful.

HR is modern priesthood, and their function is to prevent the "unwashed" from ascending up the higher ranks.

Now there I've made it much worse (or better!) than the actual reality, which is that there's just not enough quality engineering jobs no matter which way you cut it and all of this theatrics result from scarcity.

Ultimately, the problem is that every person has their own anecdata-driven or follow-the-leader-inspired ideas about how to interview effectively, and large swaths of them are in stark opposition to each other.

And now after decades of research, we're still using magic potions that mostly don't make sense.

I have question for MS people.

How do you guys view external contractors(the one with email address start with v-xxx)

I was contractor for MS for a while and it was not a very positive experience. i was kind of being forgotten and only be mentioned when convenient. I went by months without any actual real work done.

Sadly I've seen this kind of interviewing from lots of places; maybe it's a technique they teach in college or something.

Interview questions like this are useless as they are not an accurate approximation of a real work scenario. I've frozen up at a whiteboard in an interview before, and then figured it out on the drive home.

The best approach I've found is to do a send home quiz, and then ask them questions about the quiz to test understanding. The test also shows coding habits, which tells you a lot right there.

Bonus: put some typos in the quiz that don't matter. Red flag for the people that get hung up on that.

Now I understand why Microsoft, Apple, and other tech giants are slowly falling behind: they put strong candidates through a series of puzzles.

What a great way to filter out talented people. Great times. Very character building.

As I have grown older, I have realized dead-honesty is a false ideal to live by, especially when it comes to being rewarded in the capitalistic world. I know someone who reached executive level position in a major company and all of his career progress can be traced back to lying on his resume about a NASA internship he never got, which he conveniently purged later from everywhere.

I wouldn’t go that far, but I think it’s perfectly fine to reverse-engineer the interview game and reap the rewards. There’s no reason to feel guilty about it.

Sadly interviews are really aptitude and personality tests, perhaps knowledge of leetcode, tools, frameworks and languages.

In an industry that loves calling itself "engineering", it seems nothing further of value can be established?

A classically terrible interview question. Solving riddles in realtime is almost never a real job skill. _Maybe_ in an incident, but you’d be relying on tooling and experience, not an intern.

Same with leetcode at startups. It makes no sense. You’re almost certainly not going to do algorithms work. It’s only relevant if you’re looking for people willing to grind bullshit, which is certainly some jobs, but, again, you’re almost never doing this under arbitrary time pressure with someone watching over your shoulder judging and not helping.

My advice: if you encounter this, don’t work there. If a company doesn’t value testing relevant skills for candidates, don’t expect leadership to be strong critical thinkers once you get there.

Life lesson learned for OP, when it comes to tech interviewing:

(1) the riddles you already know you answer after some staged deliberation to pretend you are working it out from first principles using your genius brain (bonus points if you can work "first principles" into the conversation).

(2) The riddles you don't know the answer to are the ones you say you already read in a book or online and repeat this until you get back to a (1)

I have not seen this problem before, but the answer seems blindingly obvious? A balance is trinary, not binary. You just need to explain the decision tree.

I once had a geography teacher who had the absolutely unhinged habit of asking spontaneous gotcha questions designed to make himself look good. The kind where the question doesn't contain enough information to get to the answer he had in mind. Then when someone answered the question correctly, but didn't use the exact answer he had in mind he went all "gotcha!".

Sometimes he asked the same question again and when someone remembered the answer, he still went "gotcha!" only with a changed answer.

The lesson I learned from that guy, was that sometimes a question says more about the person asking it than about the person answering it — more precisely that men with small egos bend reality to get the outcome they prefer.

The appropriate strategy with him was to ask in a Socratic way while stroking his ego: "But haven't you thought us X is Y? I would like to get it correct!", then he would squirm around and admit that yes, this is also correct.

This type of dynamic can also occur in interviews.

Well, maybe you can use this to trick the interviewer into giving you a new problem if you don't know the first one they give you.

It's interesting to see how interviews often test more than technical skills. I probably would've made the same choice and asked for another question too man. Really enjoyed reading this.

I interviewed for an internship in 2006 and didn't get any brainteasers, but I got some pretty interesting questions that were somewhat computer science-related:

1. Suppose you have a binary tree (NOT a binary search tree) where each node with pointers to its parent and children. Given pointers to two arbitrary nodes in the tree, find their lowest common ancestor.

2. My favorite: given a uniform random number generator mod 5, create a uniform random number generator mod 7

3. Forgot the exact question, but something along the lines of: suppose you want to keep track of function arguments as you call them. How do you do that?

I got (1) and (2) and utterly failed (3). (3) is entirely trivial and basically a stated fact if you know how anything about how operating systems work, but I was a freshman in college and didn't know that function arguments got pushed on a stack in memory, so I was totally lost.

> "I told the interviewer I already knew the riddle, and I asked for another one."

The question wasn't "do you know this riddle", she just wanted the riddle answered. No need to make it more complicated.

There's no lie in withholding information never asked for. It's possible the request for a new riddle was interpreted as a ploy to get an easier riddle.

I’ve been through the Microsoft loop(s) several times over the years, and (to borrow from Tolstoy) each was unhappy in its own way. There were great people who would have been a pleasure to work with but always at least one joker in the deck. One just had to laugh because it was so obvious it wasn’t me.

I remember speeding through the loop for something closely analogous to my job at the time, only to be suddenly told by the hiring manager (who up to that time was a strong supporter) in a final interview that I wasn’t qualified. Not wanting to invest any more energy, I formally withdrew, only to get a call from him protesting why I’d do such a thing. Or being told to leave at the end of the day only to be called to drive back 20 miles immediately during dinner, and finding out later that was a mistake. Or being literally screamed at (spittle in my face!) that HPC was only MPI and nothing but MPI. Or being yelled at that Windows Server was exactly the same as an enterprise storage system like EMC/HP/Hitachi. The hits go on.

> You have 12 marbles and a balance scale.

I hate such interview questions. They have nothing to do with think one really needs to do in practice. It seems for me to be just a way for interviewers to show their intellectual superiority.

> I’m afraid I’ll never know!

The rejection was so generic and there's so much random bs that goes on it could be anything that lead to that result.

Theres a Sphinx working at Microsoft and you proved that you aren't capable of adapting to the team culture.

Microsoft is a dumpster fire. You probably dodged a bullet. Source: I work in the dumpster fire