Citadel / Citadel Securities Online Assessment
Citadel Securities' OA is auto-graded and differs sharply by track - a large rotating HackerRank coding pool for SWE, recruiter-sourced probability and stats screens for quant, a pandas/R datathon for data science, and a non-coding equity aptitude test.
Software Engineering — SWE / SDE / NG intern
Two coding problems drawn from a large rotating pool shared across the SWE, SDE and new-grad intern screens (often a resume-screen filter).
- Maximize the Minimum Gap in a Subsequence Coding · medium
- Most-Visited Position Across Sprints Coding · easy
- Maximize Cards Bought Within a Budget Coding · easy
- Shortest Substring to Rewrite for a Balanced Gene String Coding · medium
- Count Song Pairs Summing to a Whole Minute Coding · easy
- Minimum Knight Moves on an N-by-N Board Coding · medium
- Prime Factor Visitation Coding · medium
- Triplets Coding · medium
- Inversions Coding · medium
- Ways to Sum Coding · medium
- Do They Belong? Coding · medium
- Consecutive Numbers Sum Coding · medium
- First Lady of Software Coding · easy
- Math with Lego Blocks Coding · easy
- Process Execution Coding · medium
- Special Nodes Coding · medium
- Hacker's Team Coding · medium
- IPO Coding · hard
- Consistent Logs Coding · medium
- Distinct Bitwise-OR Goodness Coding · medium
- Minimum Operations to Finish Parallel Jobs Coding · medium
- Longest Subarray With All Elements Greater Than K Coding · easy
- Minimum Server Upgradation Time Coding · medium
- Maximum Workday Earnings Coding · medium
- Minimum Generation To Equalize Neural Layers Coding · medium
- Get the Groups Coding · easy
- Date Format Conversion Coding · easy
- Maximum Profit Buying One Share Per Day Coding · easy
- Validate Binary Tree And Serialize Coding · medium
- Count Subarrays Divisible by m Coding · medium
- Counting Inversions via Modified Merge Sort Coding · medium
- Maximum of Sliding Window Minimums Coding · easy
- Longest Subarray With Sum at Most K Coding · easy
Quant Research / Quant Trading — QR / QT
A roughly 15-question fill-in-the-blank quant-trader OA of probability and statistics, alongside recruiter-sourced QR phone-screen brain-teasers rather than the SWE HackerRank pool.
- Probability of no HH in N coin flips Probability · medium
- Biased-coin Bayes update Probability · medium
- Welford online mean and variance Statistics · medium
- Regression slopes and R-squared Statistics · medium
- 24 Game Coding · hard · free
- Best-of-five expected games Probability · medium
- Von Neumann fair coin from a biased coin Probability · medium · free
- Maximum drawdown of a price series Coding · medium
- Monte Carlo estimate of pi and e Probability · medium · free
- Pancake sorting Coding · medium
- Rock climber expected jumps Probability · medium
- Eight consecutive equal answers in 10 T/F Probability · medium
- Two same-colored sock pairs (4 black, 4 white) Probability · medium
- Buy/sell stock timing Coding · easy
Data Science — Datathon
A multiple-choice data-science round mixing pandas/R analysis with statistics, probability and ML theory; the 2024 version tests both Python and R rather than letting you pick one.
- Two coins, one double-headed Probability · medium
- Normal approximation to the binomial Statistics · medium
- Poisson-pulse mod-N counter Probability · hard
- Pandas isin row filter pandas/R · easy
- ggplot2 grammar of graphics pandas/R · easy
- k-medoids, Naive-Bayes and elastic-net theory ML theory · medium
Citadel / Citadel Securities OA — FAQ
What is the Citadel / Citadel Securities online assessment?
Citadel Securities' OA is auto-graded and differs sharply by track - a large rotating HackerRank coding pool for SWE, recruiter-sourced probability and stats screens for quant, a pandas/R datathon for data science, and a non-coding equity aptitude test.
What is the format of the Citadel / Citadel Securities OA?
It runs as 3 tracks (SWE / SDE / NG intern, QR / QT, Datathon). Software Engineering, Quant Research / Quant Trading, Data Science — each timed, auto-graded where applicable.
How do I practice for the Citadel / Citadel Securities online assessment?
Work the sample questions above (each with a full worked solution), then take the interactive Citadel / Citadel Securities OA practice on QuantVault. For the full interview, see the Citadel / Citadel Securities interview-questions set.