CSE Blog - quant, math, computer science puzzles

Quant, Math & Computer Science Puzzles for Interview Preparation & Brain Teasing
A collection of ~225 Puzzles with Solutions (classified by difficulty and topic)

Mar 30, 2014

Value of Pi - Estimation using Dice


Source: Asked to a friend at Goldman Sachs Quant Interview

Problem:
Estimate the value of pi using a dice



Feb 10, 2014

Coin Problem - Wolfram Mathematica Puzzle


Source: The super awesome puzzle blog by Gowtham Kumar - Puzzle Tweeter - Coin Problem who got it from Wolfram Mathematica

Problem:
Suppose you have an infinite stock of $a bills and $b bills such that g.c.d(a,b)=1. Find the largest amount of money (integer) that cannot be represented using $a and $b denominations.

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Dec 24, 2013

Determinant of Matrix (17-11)

Source: Mailed by Sudeep Kamath (EECS PhD Student, UC Berkeley, EE IITB 2008 Alumnus)

Problem:

A is a 300 x 300 matrix with 17 on the diagonal, and the rest of the entries being 11. What is det (A) ?




Dec 21, 2013

Open Ended Search Problem

Disclaimer: It is a made up problem. Not to be attempted by light hearted.

Problem:
I have a 300 word text. I have a large list of indexed strings (Length of string ~ 20, Number of strings ~ 1M). I need to figure out phrases in the 300 word text that match exactly to one of the strings in the large list of strings I have.

A naive approach:
Taking all 45000 (300 C 2) phrases, search in the large list of strings. Can we do better than this? We need to minimize calls to list of indexed strings!