Brainteasers interview questions 57 brainteasers questions from quant interviews, each with the approach, the worked solution, and the concepts it tests.
The set breaks down as 5 easy, 15 medium, 24 hard and 13 expert.
Firms that ask brainteasers questions in this bank include Jane Street, Optiver, Google, Two Sigma and Microsoft.
A question from this topic: You're in a room with three light switches. Each controls one of three light bulbs in another room. You can only enter the other room once. How do you determine which switch controls which bulb?
All topics Full question bank Drill these questions You're in a room with three light switches. Each controls one of three light bulbs in… You have 8 identical balls. 7 weigh the same, 1 is heavier. Using a balance scale only… A man is looking at a portrait. He says: 'Brothers and sisters I have none, but this… You have a 5-gallon jug and a 3-gallon jug. How do you measure exactly 4 gallons? 100 people line up to board a plane with 100 seats. The first person has lost his… You have 25 horses. You can race 5 at a time. What is minimum number of races to find the… You are given 12 balls, one of which is either heavier or lighter. Using a balance scale… A rope burns non-uniformly and takes 1 hour to burn from end to end. How do you measure… You have two hourglasses: 7-minute and 11-minute. How do you measure 15 minutes? There are 10 bags of coins. One bag contains all counterfeit coins weighing 1.1 grams… Solve: dy/dx = y^2, y(0)=1. Compute ∫_0^∞ e^{-x^2} dx. Find sum of 1 + 1/2 + 1/4 + 1/8 + ... What is e^{iπ}? How many trailing zeros in 100!? Five pirates, P1 the most senior down to P5, divide 100 gold coins. P1 proposes a split… A coin lands heads with probability 1/3. Two players alternate flips and the first to… Normal play Nim with piles of 3, 5 and 7, where the player taking the last object wins… A pile has 100 stones. Players alternately remove 1, 2 or 4 stones, and whoever takes the… A company is worth V to its owner, where V is uniform on [0, 100] and known only to him… Two players alternately place identical circular coins on a circular table. Coins may not… You must show a two sided market on the sum of two fair dice to a counterparty who has… An asset is worth 0 or 100 with equal probability. Each order comes from an informed… A shuffled deck of 26 red and 26 black cards is dealt face up one card at a time. Before… A fair die is rolled repeatedly until the first 6 appears. You are then told that every… 100 prisoners are numbered 1 to 100. A room holds 100 boxes in a row, each containing one… 100 prisoners stand in a line, each wearing a hat of one of 10 colours. Each sees only… Countably many people stand in a line indexed 1, 2, 3 and so on. Each wears a black or… 100 prisoners enter a room one at a time in an order chosen adversarially, each entering… You have a balance scale and a set of identical looking balls, exactly one of which is… You have 2 identical eggs and a 100 floor building. An egg breaks if dropped from any… I pick a whole number from 1 to 1000. You ask adaptive yes or no questions and I answer… Four people must cross a bridge at night with one torch. The bridge carries two at a… A jeep carries fuel for exactly 100 km in a full tank and may leave fuel in the desert to… A trader has 3000 bananas and a camel that carries at most 1000 at a time and eats 1… Two squares of opposite colour are removed from an 8 by 8 chessboard, anywhere on the… Remove any single square from an 8 by 8 board. Can the remaining 63 squares always be… A room is 30 ft long with square end walls 12 ft by 12 ft. A spider sits on one end wall… An island holds 100 blue eyed and 100 brown eyed people, all perfect logicians. Nobody… A judge tells a prisoner he will be hanged at noon on one weekday next week and that the… An ant starts at one end of a rubber band 1 km long and crawls toward the far end at 1 cm… A drunkard takes a simple symmetric random walk on the integer lattice, one step per… 100 candidates are interviewed one at a time in random order, and after each you know… The pirate game with 100 gold coins, where a proposal passes when at least half the… A host and his spouse invite four other couples. People shake hands with some of the… Prove that in any group of 6 people, some 3 are mutual acquaintances or some 3 are mutual… From the numbers 1 to 100, what is the largest subset you can choose in which no element… A 10 by 10 board has area 100, which 4 divides, so the count alone permits a tiling by 25… Two trains 100 km apart move toward each other at 50 km/h each. A fly starts on the front… You stand on a bathroom scale inside a lift. At rest the scale reads 80 kg. While the… A rower on a river drops a bottle overboard and carries on upstream at a constant speed… An even number of coins with known values lies in a row. Players alternately take one… Misere Nim with piles of 1, 1, 1 and 5, where the player who takes the last object loses… You roll a fair six sided die and may take the number shown in dollars or reroll, with at… Chomp is played on an m by n grid. A move names a square and removes it together with… A jar has an unknown value V with a flat prior. Each of 10 bidders sees an independent… Five bags each hold many coins. Every bag is either all genuine at 10 g per coin or all…