Jane Street Interview Questions

Note: ensure you read the disclaimer on the previous page reading the accuracy and sourcing of these problems.

Course Prerequisites

Here's a classic challenge that comes up in real life interviews surprisingly often. Interviewers like it as a way to assess your ability to find the right data structure for a non obvious and non trivial use case. The prompt is as follows: you're a university student currently trying to plan th...

Difficulty: 8/10

Stock Buy and Sell Optimization

This is a classic technical interview question that I've seen a number of times in real life interviews. Let's say you're given an array of stock prices, with each element being an integer that represents a price in dollars. 10, 7, 6, 2, 9, 4 Each index of the array represents a s...

Difficulty: 5/10

K Largest Elements From List

We're given a list or array of numbers, like the following: const nums 5, 16, 7, 9, 1, 4, 3, 11, 2 Can you write an algorithm to find the k largest values in a list of n elements? If k were 3 , we'd want the three largest numbers returned. The correct logic would return 16, 11, 9 ....

Difficulty: 5/10

Hoisting and Call Stack

Understanding Variable Scoping in JavaScript Let's dig into a fascinating JavaScript example to unravel the mystery of variable scoping. The Code Snippet Here's the code we'll be examining: javascript var numOfBeers 5 function getMoreBeers console.log 'I have this many beers: ...

Difficulty: 7/10

Levenshtein Edit Distance

An edit distance is a way to quantify how different two strings are. This is calculated using **the minimum number of transformations to turn one string to another**. The transformations include insertion , deletion , and substitution . So when comparing two identical strings, say cat and ca...

Difficulty: 7/10

Single Lonely Number

In a given array of numbers, one element will show up once and the others will each show up twice. Can you find the number that only appears once in O n linear time? Bonus points if you can do it in O 1 space as well. lonelyNumber 4, 4, 6, 1, 3, 1, 3 6 lonelyNumber 3, 3, 9 9...

Difficulty: 3/10

Decimal To Binary

Today, we're going to do some math! There is only one prerequisite for answering this question, and it is knowing the definitions of binary and decimal . According to How to Convert Decimal to Binary and Binary to Decimal https: techterms.com definition binary , binary is a numeric system th...

Difficulty: 5/10

Serialize and Deserialize a Binary Tree

Given a binary tree representation, can you come up with a method to serialize the tree and then deserialize it to get the exact same tree? What is Serialization and Deserialization? Serialization is a process that converts a data structure to a suitable format that can be stored either ...

Difficulty: 8/10

Max Leaps in Jump Game

We have an array that model square blocks on a city street. On each block is a non negative whole number. Ever heard of hopscotch? Picture that as an array: 1, 3, 2, 2, 1 Now, in hopscotch, you need to jump in patterns from the start to the end of the boxes. We can model that behavior in the...

Difficulty: 5/10

Getting Your First Software Job Without Professional Experience

I ve had a few friends recently ask me about breaking into the software industry. Most have been looking for advice on getting a developer job at a consumer facing web internet company though places like Tesla and WeWork are also very popular. These friends have probably heard about the amazin...

Difficulty: 5/10

Introduction to Databases

Introduction to Databases As a senior backend engineer, you may have encountered situations where handling data efficiently and effectively is crucial. Databases play a fundamental role in managing and organizing large amounts of data. In this lesson, we will explore the theoretical concepts be...

Difficulty: 5/10

JavaScript Basics

Introduction to JavaScript JavaScript is a lightweight, text based programming language that adds interactivity to websites. It cannot execute independently, that is, it requires the support of another language HTML for execution. Here's an example of a simple JavaScript program: js con...

Difficulty: 5/10