Are brain teasers still asked in coding interviews?

Mostly no, and quietly yes. Google publicly banned brain teasers from its interviews over a decade ago, and the other large tech companies followed. But the puzzles never died; they migrated. Quant firms and trading shops still ask them outright, and big tech re-asks them in disguise, wrapped inside algorithm questions that test the identical reasoning. Preparing for the reasoning still pays.

I want to defend that second half, because the first half gets all the press. When people cite the death of the brain teaser, they are usually quoting Laszlo Bock, Google's former head of People Operations, who said in 2013 that questions like "how many golf balls fit in a school bus" were a complete waste of time and served primarily to make the interviewer feel smart. He was right about those questions. He was not making a claim about the two ropes, the 25 horses, or the egg drop, and the difference between the two categories is the most useful thing this essay has to offer.

Did big tech actually stop asking brain teasers?

As formal policy, yes. Google's internal analysis found zero correlation between brain-teaser performance and job performance, and its interviewer guidelines have prohibited them since around 2013. Amazon's interviewer training says the same. Meta, Microsoft, and Apple scrubbed them from their loops in the same era; Microsoft is the ironic case, since its 1990s loop popularised the genre and an entire book, William Poundstone's How Would You Move Mount Fuji?, was written about it.

The stated reason is predictive validity. A question you have either seen or not seen measures exposure, not ability. A candidate who recites the 17-minute bridge schedule proves they read the same forums as everyone else. Structured coding questions, where the interviewer can watch you decompose a fresh problem step by step, predicted on-the-job performance far better in every dataset these companies collected. So the official line hardened: no riddles, no gotchas, no Mount Fuji.

Why do interviewers still ask them anyway?

Because policy governs the question bank, not the skill being probed, and because not every employer adopted the policy. Three places the classic teaser survives in 2026:

First, quantitative finance. Jane Street, Citadel, Optiver, and their peers ask probability and deduction puzzles as a core round, unapologetically. Their defence is that the puzzles resemble the actual job: fast, adversarial reasoning about a toy model under time pressure. Whatever you think of that argument, the empirical fact stands, and candidates who skip puzzle practice walk into those screens cold.

Second, the warm-up and the culture question. Plenty of individual interviewers at companies whose official banks are teaser-free still open with something light, and a rope or lightbulb puzzle fills that slot. It is rarely scored. It still shapes the interviewer's impression, and impressions leak into hire decisions whether the rubric admits it or not.

Third, and most important: the disguised version. Modern interview banks are full of questions that are classic teasers wearing an engineering costume. The disguise is thin once you look for it.

What do brain teasers look like when they are disguised?

They look like medium-hard algorithm questions. The tell is that the coding is trivial once you have the insight, and the insight is the old puzzle's insight. Some direct lineages:

Classic teaser	The skill it probes	Its modern interview costume
Two-egg drop, 100 floors	Balancing unequal worst-case costs	"Super Egg Drop" as a dynamic programming question
25 horses, 5 lanes	Selection without full ordering	Top-k problems, tournament arguments, quickselect
100 bulbs toggled by 100 people	Changing the unit of analysis	Divisor-counting and "Bulb Switcher" one-liners
Bridge and torch at night	Distrusting greedy, exchange arguments	Greedy-with-proof scheduling questions
Mislabeled jars	Constraint propagation before observation	Deduction over invariants, minimum-queries problems

The right-hand column is squarely inside today's interview canon. When an interviewer asks the egg-drop question as dynamic programming, they are asking a 1960s puzzle with a memo table attached; the recurrence falls out only after you see the worst-case balancing idea, which is the puzzle. When they ask for the third-largest element with a no-full-sort constraint and push you toward a proof, they are asking the horses question. I walk through both proofs in the interview patterns essay, and the search-space version of the egg-drop idea has its own treatment in binary search on the answer.

So the honest answer to this essay's title question is: the questions were renamed, not retired. A candidate who dismisses puzzles as obsolete trivia and a candidate who memorises fifty answers are making the same mistake, treating the answer as the asset. The asset is the move that produces the answer.

How should you prepare for brain teasers in 2026?

Practise the moves, out loud, on puzzles you have not seen. The classic teasers reduce to a small set of reusable moves, and each one transfers directly to algorithm questions:

Find the invariant. Ask what stays fixed while everything else varies. The burning ropes are chaos along their length but conserve total burn time, and the whole solution lives in that conserved quantity. This is the same discipline as loop-invariant reasoning in code, and it is the move interviewers most reward when they can watch it happen.

Count the states. Before hunting for a clever scheme, count how many outcomes an observation can distinguish and how many hypotheses you must separate. One bulb inspection cannot separate three switches unless the bulb carries more than one bit. One fruit cannot separate six jar arrangements, so first check how many arrangements the constraints already eliminated. The identical count shows why comparison sorting cannot beat n log n.

Change the unit of analysis. When a process is narrated as a timeline, try fixing one element and asking what the whole process did to it. The 100-bulbs puzzle collapses from a simulation into a divisor-counting question the moment you stare at one bulb, which is precisely the reframe behind frequency counting.

Distrust greedy until it survives an exchange argument. The bridge puzzle's ferry strategy is locally sensible and globally wrong, and the fix is to compare two candidate schedules term by term. That is the same proof obligation a correct greedy algorithm must discharge.

Then practise delivery. In the room, narrate your constraints before your ideas, state what would falsify your current approach, and when you recognise a question, say so; interviewers respond far better to "I know this one, want me to prove the bound instead?" than to badly staged theatre of discovery. A puzzle a day, attempted honestly before reading hints, builds exactly this muscle. That cadence is why we publish one, with graduated hints so you can take the smallest nudge that unsticks you rather than the full answer.

Frequently asked questions

Do FAANG companies ask brain teasers in 2026?

Not as official, scored questions; their interviewer guidelines have prohibited riddles for years. You may still meet one as an unscored warm-up, and you will meet their reasoning constantly inside algorithm questions such as egg-drop dynamic programming or top-k selection with a proof requirement.

What is the difference between a brain teaser and a gotcha question?

A gotcha depends on one hidden fact or pun and teaches nothing when revealed. A genuine teaser is solvable by systematic reasoning from stated constraints, and its solution generalises. "Why are manhole covers round" is a gotcha; the two ropes reward an invariant argument you can reuse for the rest of your career.

Should I memorise the classic brain teaser answers?

Know the famous ones, since pretending otherwise wastes interview time, but study the method that produces each answer and rehearse it on unfamiliar puzzles. Interviewers routinely change the numbers, and the bridge puzzle's optimal strategy flips entirely under different walking speeds; a memorised answer fails exactly there.

If you want the daily rep, start with the archive's hardest deduction chain, the 25 horses puzzle, then carry the same selection argument into real code with the quickselect deep-dive.