Jane Street Interview Questions
Practice 53 real Jane Street interview questions for 2026 — Jane Street interview questions and interview preparation built from real problems used in actual interviews with detailed solutions. This collection emphasizes coding-first assessment, trading-flavored probability and puzzle questions, and ML/statistics tasks that mirror the firm’s focus on precision, speed, and clear reasoning. Expect short, whiteboard-style problem solving and paired coding that tests correctness, edge-case thinking, and clear verbalization of tradeoffs; prepare by sharpening algorithmic coding, probability modeling, time-series intuition, and concise system designs. Software engineering content dominates: problems repeatedly ask you to transform sparse time-stamped streams into dense rows, validate and canonicalize order-book/trade data across databases, and design low-latency message flows between exchanges and trading systems, plus implementation puzzles (e.g., Connect Four) and probability/game-theory questions. Data scientist questions cluster around real-vs-fake DNA classifiers, probability and queueing puzzles, and trading RFQ competitiveness analysis. Machine learning engineering questions focus on end-to-end training frameworks, time-series forecasting for trading, and small runtime/compiler design for domain-specific languages.
"I got asked a hardcore MCM DP question and I saw it on PracHub as well. Solved that question in 5 minutes. Without PracHub I doubt I could solve it in 5 hours. Though somehow didn't get hired, perhaps I guess I solved it too fast? /s"
"Believe me i'm a student here jn US. Recently interviewed for MSFT. They asked me exact question from PracHub. I saw it the night before and ignored it cause why waste time on random sites. I legit wanna go back and redo this whole thing if I had chance. Not saying will work for everyone but there is certainly some merit to that website. And i'm gonna use it in future prep from now on like lc tagged"
"10 years of experience but never worked at a top company. PracHub's senior-level questions helped me break into FAANG at 35. Age is just a number."
"I was skeptical about the 'real questions' claim, so I put it to the test. I searched for the exact question I got grilled on at my last Meta onsite... and it was right there. Word for word."
"Got a Google recruiter call on Monday, interview on Friday. Crammed PracHub for 4 days. Passed every round. This platform is a miracle worker."
"I've used LC, Glassdoor, and random Discords. Nothing comes close to the accuracy here. The questions are actually current — that's what got me. Felt like I had a cheat sheet during the interview."
"The solution quality is insane. It covers approach, edge cases, time complexity, follow-ups. Nothing else comes close."
"Legit the only resource you need. TC went from 180k -> 350k. Just memorize the top 50 for your target company and you're golden."
"PracHub Premium for one month cost me the price of two coffees a week. It landed me a $280K+ starting offer."
"Literally just signed a $600k offer. I only had 2 weeks to prep, so I focused entirely on the company-tagged lists here. If you're targeting L5+, don't overthink it."
"Coaches and bootcamp prep courses cost around $200-300 but PracHub Premium is actually less than a Netflix subscription. And it landed me a $178K offer."
"I honestly don't know how you guys gather so many real interview questions. It's almost scary. I walked into my Amazon loop and recognized 3 out of 4 problems from your database."
"Discovered PracHub 10 days before my interview. By day 5, I stopped being nervous. By interview day, I was actually excited to show what I knew."
"I recently cleared Uber interviews (strong hire in the design round) and all the questions were present in prachub."
"The search is what sold me. I typed in a really niche DP problem I got asked last year and it actually came up, full breakdown and everything. These guys are clearly updating it constantly."
Connect-N on an Infinite Board with Gravity
You are asked to implement a variant of the classic Connect Four game, played on an unbounded board. Game Rules - The board consists of vertical colum...
Quant Probability Brainteasers: Pizza Bounds, Coin Scores, Ant on a Cube, Shoelace Loops, and Paint Mixing
You are in a quantitative research interview. The interviewer works through a series of short probability puzzles and expects you to reason out loud, ...
Field Layout: getOffset and insert
An object's binary layout is defined by an ordered list of fields. Each field has a unique name and a size in bytes. Fields are packed contiguously st...
Decode an Encrypted Paragraph Tree
Decode an Encrypted Paragraph Tree A document is stored as a tree of paragraphs. Each node holds a paragraph text — a string of lowercase English lett...
Merge Two Insertion Diffs in Linear Time
A text-editing system represents changes to a document as insertion diffs. An insertion diff is a set of (position, value) pairs, where each pair mean...
Stack Machine Interpreter with Typed Int and String Values
You are building an interpreter for a simple stack machine. The machine has a single stack, and every value on the stack is one of exactly two primiti...
Reach a Target Using Each Number At Most Once
Reach a Target Using Each Number At Most Once You are given an array of integers nums and an integer target. Decide whether you can build an arithmeti...
Evaluate a Tokenized Arithmetic Expression
Evaluate a Tokenized Arithmetic Expression You are given an arithmetic expression that has already been tokenized for you — you do not need to write a...
Use Excel formulas to compute haircuts
You are given an Excel worksheet with columns such as Asset, Market Value, and Haircut %. Using only cell references (no copy-paste of numeric values)...
Optimal Stopping for Die Rolls That Bust on Perfect Squares
You repeatedly roll a fair six-sided die and keep a running cumulative sum $S$ of all the values rolled so far (starting from $S = 0$ before the first...
Two Opaque Boxes: Place or Take for Maximum Expected Payoff
You are playing a one-player game with two opaque boxes, both of which start empty. The game lasts exactly 100 turns, and on every turn you must choos...
Streaming Equivalence of Two Trade Feeds with Per-Company Ordering
A market-data system receives trade events from two independent feeds. Each event is a pair (company, trade_id) identifying one trade for one company....
Snake Game: Minimum Moves to Reach the Apple
Snake Game: Minimum Moves to Reach the Apple You are simulating the classic Snake game on a grid with R rows and C columns. Cells are identified as (r...