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Quant Guide

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Quant Guide

Quant traders and quant researchers both face challenging interviews that test far more than basic math. These selected problems guide quants to practice the concepts that matter most. Unlike discretionary traders, quant traders rely on mathematical models and coding rather than intuition. Their interviews emphasize fast problem-solving with probability puzzles, brainteasers, math challenges, and coding tasks. Quant researchers focus more deeply on models and longer-term projects, which is why their knowledge of statistics, linear algebra, and advanced programming is assessed.

305 questions in this plan
Brain Teasers 34 questions
Question Subcategory Difficulty Status
100 Light Bulbs Symmetry Medium
Back to Starting Point Logical Medium
Birthday Puzzle #2 Logical Hard
Calendar Dice Out of the Box Medium
Clocks and Hands Logical Medium
Door to Offer Out of the Box Hard
Escape Plan Out of the Box Medium
Farmers' Land Logical Medium
First Person to Say 50 Logical Medium
Fishermen Logical Hard
Fox vs. Duck Logical Medium
Example
Horse Race Logical Medium
House of Cards Summation Easy
How Many Twos Simplification Medium
Infinite Chessboard Out of the Box Hard
Knights and Knaves Logical Easy
Pirates Dividing a Treasure Simplification Medium
Example
Prisoner Problem #1 Modular Hard
Prisoner Problem #2 Modular Hard
Rabbit Climbing the Stairs Logical Easy
Salary Voting Logical Medium
Sandglass Logical Medium
Subset of Numbers Logical Hard
Tennis Match Mystery Logical Hard
The King's Party Out of the Box Medium
Example
The Last Chocolate Game Logical Hard
Trailing Zeros Logical Medium
Transfer 3000 Apples Logical Hard
Two Glass Balls Summation Medium
Waiting for the Train Logical Medium
Water and Wine Logical Easy
Water Jugs Logical Medium
Weighing Blocks Logical Easy
Which Day Logical Hard
Probability and Statistics 108 questions
Question Subcategory Difficulty Status
100-Sided Die Expected Value Hard
230 Heads General Medium
Aces for All Combinatorial Analysis Easy
Animal Migrations Markov Chain Probability Easy
Are We There Yet Game Theory Medium
Athletic Cats Conditional Probability Medium
Basketball Practice #1 Expected Value Medium
Basketball Practice #2 Expected Value Hard
Beach Carts Game Theory Easy
Beat the Odds Game Puzzle Hard
Beta Gap General Medium
Biased Coin #1 Expected Value Medium
Biased Coin #2 Expected Value Easy
Biased Coin #3 Expected Value Easy
Biased Coin #4 Expected Value Medium
Bold Betting Strategy Markov Chain Probability Medium
Building the Book Game Theory Medium
Bullseye Bet Expected Value Medium
Candle Batch General Medium
Capsule Colors Expected Value Easy
Challenger's Gambit Game Theory Medium
Cherry Streak General Medium
Coefficient of Variation Expected Value Hard
Coin Toss #1 Conditional Probability Medium
Correlation Flip General Medium
Covariance Ceiling General Easy
Diagonal Duel General Medium
Diamond Variance Expected Value Medium
Dice Game #1 Expected Value Hard
Dice Game #2 Expected Value Hard
Dice vs Coins Expected Value Medium
Dice With Same Numbers Expected Value Medium
Example
Dominant Game Markov Chain Probability Hard
Drunk Student #2 Expected Value Medium
Engine or Wheels Conditional Probability Easy
Escape the Square Markov Chain Probability Hard
Exponential Distribution #1 Expected Value Medium
Exponential Distribution #2 General Medium
Faster Sixes Expected Value Hard
First to Heads Conditional Probability Medium
Five Deck Straight Combinatorial Analysis Medium
Flip 4 Coins Expected Value Medium
Flowers in Bloom Expected Value Medium
Four Digit Difference General Hard
Four Fives #1 General Easy
Four Fives #2 General Easy
Free Ticket Expected Value Hard
Going to the Beach #2 General Hard
Half the Average Game Theory Medium
Heavier Side Combinatorial Analysis Medium
Higher Card General Medium
How Many Children General Hard
How Many Pairs Combinatorial Analysis Hard
Jumping Robots General Hard
Latency Arms Race Game Theory Easy
Meeting Your Friend Combinatorial Analysis Medium
Mismatched Dice General Easy
Old Phone #2 General Medium
Old Scale Combinatorial Analysis Easy
Optimal Spread General Hard
Overbooked Flight Combinatorial Analysis Medium
Painted Cube Conditional Probability Hard
Parking Meter Markov Chain Probability Easy
Picking Balls #2 Combinatorial Analysis Medium
Picking Balls #3 Combinatorial Analysis Medium
Picking Tiles Markov Chain Probability Easy
Quoting Duel Game Theory Medium
Racing Cars Conditional Probability Medium
Radar Sweep General Medium
Random Ant Markov Chain Probability Medium
Example
Redundant Quote Game Theory Hard
Region Spinner Markov Chain Probability Easy
Remaining Coins Expected Value Medium
Rising Chips Combinatorial Analysis Medium
Running Rabbit Combinatorial Analysis Medium
Second Heads Conditional Probability Medium
Specific Card #2 Combinatorial Analysis Medium
Spin in Two Regions Expected Value Medium
Spread Truce Game Theory Hard
Stop Sign Stroll Markov Chain Probability Medium
Subset Makes Six Combinatorial Analysis Hard
Sum Seventeen Combinatorial Analysis Hard
Ten Cards, No King Combinatorial Analysis Easy
Tennis Game General Medium
Example
Tennis Match: Win in 2 or 3 Sets General Medium
Tennis Odds Game Puzzle Hard
The Drunkard's Walk Markov Chain Probability Hard
The Highest Face Expected Value Medium
Three Blue Orbs Expected Value Medium
Three Cards Difference Combinatorial Analysis Hard
Throw a 6 #2 Expected Value Medium
Throw a 6 #3 Expected Value Hard
Throw Until Matched Expected Value Medium
Example
Top 2000 Songs Markov Chain Probability Medium
Triple Match Combinatorial Analysis Medium
Twice as Likely Conditional Probability Medium
Two Consecutive Fives Expected Value Medium
Two Dice Difference Expected Value Easy
Two Hues Left Expected Value Hard
Two Rolls Payoff Expected Value Easy
Unfair Heads #2 Conditional Probability Medium
Uniform Distribution #1 Expected Value Hard
Vacant Room Conditional Probability Hard
Wheel of Eights Combinatorial Analysis Medium
Which Die Was It Conditional Probability Medium
Who Calls the Landlord Game Theory Hard
Whose Turn Is It Game Theory Easy
Widening Wheel Expected Value Hard
Programming 54 questions
Question Subcategory Difficulty Status
All Pairs Array and List Processing Easy
Example
All Permutations Array and List Processing Medium
All Vowels String Manipulation Easy
Arithmetic Mean Array and List Processing Hard
Balanced Brackets Other Easy
Binary Search Tree (BST) Array and List Processing Hard
Circular Queue Implementation Other Hard
Common Prefix Algorithm String Manipulation Medium
Consecutive Letters String Manipulation Medium
Counting Inversions Array and List Processing Hard
Counting Islands Graphs Medium
Count Number of Homogenous Substrings String Manipulation Medium
Course Schedule Graphs Hard
Crate Loading Array and List Processing Easy
Dijkstra's Algorithm #1 Graphs Hard
Example
Dijkstra's Algorithm #2 Graphs Hard
Drawing a Blue 3 Mathematical Problems Medium
Empty Number of Boxes Mathematical Problems Medium
Evaluate RPN Other Medium
Fewest Coins Mathematical Problems Medium
Find All Paths Graphs Hard
Finding the Largest Possible Number Array and List Processing Easy
Find the Missing Number Array and List Processing Easy
Group Anagrams String Manipulation Medium
Hex Word String Manipulation Easy
Last Node of Singly Linked List Other Medium
Linked List Cycle Other Medium
Longest Common Subsequence (LCS) Array and List Processing Medium
Example
Longest Increasing Subsequence Array and List Processing Hard
Longest Run of Distinct Characters String Manipulation Medium
Majority Element Array and List Processing Medium
Maximum Subarray Sum Array and List Processing Medium
Minimum Spanning Tree (MST) Graphs Hard
Optimal Stopping Strategy Mathematical Problems Medium
Palindrome Checker String Manipulation Medium
Pricing Accuracy Mathematical Problems Medium
Prime Number Generator Mathematical Problems Medium
Priority Queue Using Heaps Other Hard
Example
Reverse a Linked List Other Easy
Roulette Table Mathematical Problems Medium
Search a Rotated Array Array and List Processing Medium
Settling Array Array and List Processing Medium
Smallest String String Manipulation Easy
Sorting Without Sort() Array and List Processing Hard
Streaming Median Other Hard
Subarray Sum Equals Zero Array and List Processing Medium
Sudoku Array and List Processing Hard
Summing Up Strings #1 String Manipulation Hard
Summing Up Strings #2 String Manipulation Hard
Top 2000 Songs Mathematical Problems Medium
Validate a BST Other Medium
Weather API Data Analyzer Other Hard
Word Frequency String Manipulation Easy
Words in a String String Manipulation Medium
Math Questions 23 questions
Question Subcategory Difficulty Status
Boats on a River General Hard
Choosing Blocks General Easy
Escalator Steps General Medium
Example
Fly vs Ant General Medium
How Many Dogs General Medium
Inflate Rate General Hard
Example
Jumping Frog General Medium
Magic 37 General Hard
Number of Pigs General Easy
Example
Product of Unknowns #1 Solving Unknowns Hard
Radius of a Circle General Hard
River Length #1 General Medium
River Length #2 General Medium
Sequences General Easy
Set of Distinct Integers General Easy
Sharing a Glass General Easy
Sheep Runs Home General Hard
Spread Set General Hard
Squares On Chessboard General Medium
System of Weights Solving Unknowns Medium
Triangle on Circle General Medium
Unfolded Box General Hard
Upstream or Downstream General Medium
Machine Learning 62 questions
Question Subcategory Difficulty Status
AdaBoost by Hand Ensemble Methods Hard
Backpropagation by Hand Neural Networks Hard
Bagging: Why Averaging Reduces Variance Ensemble Methods Medium
Batch, Stochastic and Mini-Batch Gradient Descent Optimization Medium
Bias-Variance Tradeoff Model Fundamentals Easy
Calibrated Probabilities Model Evaluation Medium
Cointegration, Not Correlation Time Series Hard
Deriving OLS Linear Models Hard
Dropout, Weight Decay, and Early Stopping Deep Learning Easy
Elastic Net and Correlated Features Regularization Medium
Encoding Categorical Variables (and the Target-Encoding Trap) Feature Engineering Medium
Entropy, Cross-Entropy and KL Divergence Foundations Medium
Exploration versus Exploitation Reinforcement Learning Medium
Forests vs Boosting Ensemble Methods Medium
Fractional Differencing Weights From Scratch Financial ML Hard
From Likelihood to Loss Foundations Easy
Gradient Descent From Scratch Optimization Medium
Handling Missing Values Feature Engineering Easy
How a Decision Tree Chooses a Split Classic Algorithms Easy
How Many Backtests Is Too Many? Backtesting & Validation Hard
How Many Principal Components? Dimensionality Reduction Medium
Identifying an ARIMA Model Time Series Medium
Is This Series Stationary? Time Series Easy
k-Nearest Neighbours From Scratch Classic Algorithms Easy
kNN vs k-Means Classic Algorithms Easy
Labelling Financial Data Financial ML Medium
Leakage-Free Pipeline Coding Medium
Logistic Regression From Scratch Classification Hard
Lookahead Bias Backtesting & Validation Medium
Markov Decision Processes and the Bellman Equation Reinforcement Learning Medium
Maximum Likelihood Estimation for a Gaussian Foundations Medium
MDI versus MDA Feature Importance Easy
Multicollinearity and the Variance Inflation Factor Linear Models Medium
Naive Bayes From First Principles Classification Medium
Newton's Method and Second-Order Optimization Optimization Hard
One-Step GARCH(1,1) Forecast Time Series Medium
One LSTM Step by Hand Deep Learning Hard
Order Book Feature Engineering Feature Engineering Easy
Principal Component Analysis Dimensionality Reduction Hard
Purged and Embargoed K-Fold Backtesting & Validation Hard
Q-Learning for Market Making Reinforcement Learning Hard
Reading the ROC Curve Model Evaluation Medium
Ridge Regression as a Gaussian Prior Regularization Hard
Ridge vs Lasso Regularization Medium
Rolling Z-Score Without Look-Ahead Coding Medium
Scaled Dot-Product Attention by Hand Deep Learning Medium
Self-Attention From Scratch Deep Learning Hard
Stationary but with Memory Financial ML Medium
t-SNE and UMAP: Nonlinear Embeddings Dimensionality Reduction Medium
The Accuracy Trap Model Evaluation Easy
The Curse of Dimensionality Model Fundamentals Medium
The Gauss-Markov Theorem Linear Models Hard
The Substitution Effect Feature Importance Hard
The SVM Margin and the Kernel Trick Classification Hard
The Unit Root Time Series Hard
The Vanishing Gradient Problem Deep Learning Easy
Vectorization and Broadcasting Coding Easy
Weight Initialization: Xavier and He Neural Networks Medium
What SHAP Values Actually Compute Feature Importance Hard
Why Adam? Deep Learning Medium
Why a Tiny R-Squared Makes Money Model Fundamentals Easy
Why Do We Need Non-Linear Activations? Neural Networks Easy