Free practice library
Interview practice
Solve complete questions with progressive hints, worked solutions and Python implementations. Each question explains its assumptions and source match. Original interpretations are labelled explicitly.
752
Ready to practise
174
Not yet playable
926
Catalogue titles
Public standard problems and original exercises; hidden Trading Interview questions have not been verified.
174 titles have been investigated but remain unresolved. Their missing details are recorded without adding substitute exercises. Every playable question has a guided animated answer; selected questions also have custom diagrams.
Practise Learnr’s own questions →Follow a role-specific curriculum →752 matching entries · page 1 of 16
Programming · Medium
Maximum Subarray Sum
Supported standard problem · Match confidence: high
About this question’s source match
The title and Programming / Array and List Processing classification fit the linked public problem. This entry uses an independently worded practice statement and original implementation. The public title and category identify a standard problem family; the private Trading Interview statement has not been inspected.
Implement solve(nums) returning the greatest sum of a nonempty contiguous subarray. Reject empty input with ValueError. Negative entries are allowed.
Assumptions and constraints
- At least one element is required.
- 1 <= n <= 1000000
Examples
nums=[-5,3,-1,4,-8] → 6
The subarray 3,-1,4 sums to 6.
Company evidence · unverified
No company-specific source has been matched to this exercise. Its references support the topic or solution method; they do not establish employer use.
References
Read the supporting material without leaving your question.
leetcode.com
Maximum Subarray — LeetCodePublic problem definition only; Learnr examples, boundary extensions, solution explanation and implementation are independently authored. Does not establish the private catalogue statement.
- Medium
1 to 7
Brain Teasers · Out of the Box
Researched · playable - Medium
100 Light Bulbs
Brain Teasers · Symmetry
Researched · playable - Hard
100-Sided Die
Probability and Statistics · Expected Value
Researched · playable - Medium
230 Heads
Probability and Statistics · General
Researched · playable - Medium
24/7 And Fragmented
Digital Assets - Crypto · Digital Assets Knowledge
Researched · playable - Easy
3 Unique Marbles
Probability and Statistics · Combinatorial Analysis
Researched · playable - Easy
3-Factor and 5-Factor Models
Asset Pricing · Factor Models
Researched · playable - Medium
5 Descending Cards
Probability and Statistics · Expected Value
Researched · playable - Easy
51% Attack
Digital Assets - Crypto · Blockchain Technology Fundamentals
Researched · playable - Medium
90 Cents Please
Probability and Statistics · Combinatorial Analysis
Researched · playable - Easy
About the Firm
Behavioral Questions · General
Researched · playable - Easy
Aces for All
Probability and Statistics · Combinatorial Analysis
Researched · playable - Medium
Active, Passive and Beta ETFs
Derivatives Theory · ETF Theory
Researched · playable - Hard
AdaBoost by Hand
Machine Learning · Ensemble Methods
Researched · playable - Easy
Advantages ETFs
Derivatives Theory · ETF Theory
Researched · playable - Easy
Air Hockey Deadlock
Probability and Statistics · Combinatorial Analysis
Researched · playable - Easy
Airdrop
Digital Assets - Crypto · Digital Assets Knowledge
Researched · playable - Easy
Airplane Food
Probability and Statistics · Combinatorial Analysis
Researched · playable - Easy
Airport Cafe
Probability and Statistics · Conditional Probability
Researched · playable - Easy
All Bulbs Lit
Probability and Statistics · Conditional Probability
Researched · playable - Easy
All Faces
Probability and Statistics · General
Researched · playable - Easy
All Pairs
Programming · Array and List Processing
Researched · playableJane Street · Topic guidanceCitadel · Topic guidanceCitadel Securities · Topic guidance - Medium
All Permutations
Programming · Array and List Processing
Researched · playable - Easy
All Vowels
Programming · String Manipulation
Researched · playable - Easy
All-Boys City
Probability and Statistics · General
Researched · playable - Easy
Altcoins
Digital Assets - Crypto · Digital Assets Knowledge
Researched · playable - Easy
American vs. European Options
Derivatives Theory · Option Theory
Researched · playable - Medium
AMM Swap Math
Digital Assets - Crypto · Digital Assets Knowledge
Researched · playable - Easy
Analog Clock Angle
Math Questions · General
Researched · playable - Easy
Animal Migrations
Probability and Statistics · Markov Chain Probability
Researched · playable - Easy
Ants on a Stick
Brain Teasers · Out of the Box
Researched · playable - Easy
Any Cake Left
Probability and Statistics · General
Researched · playable - Medium
Applying Singular Value Decomposition (SVD)
Linear Algebra · Use Case
Researched · playable - Medium
Arbitrage In Crypto
Digital Assets - Crypto · Digital Assets Knowledge
Researched · playable - Easy
Archery Rotation
Probability and Statistics · Conditional Probability
Researched · playable - Medium
Are We There Yet
Probability and Statistics · Game Theory
Researched · playable - Hard
Arithmetic Mean
Programming · Array and List Processing
Researched · playable - Easy
ATM at Maturity
Derivatives Theory · Greeks
Researched · playable - Medium
ATM to ITM Call
Derivatives Theory · Greeks
Researched · playable - Medium
ATM to OTM Put
Derivatives Theory · Greeks
Researched · playable - Medium
Atomic Swap
Digital Assets - Crypto · Digital Assets Knowledge
Researched · playable - Medium
Back to Starting Point
Brain Teasers · Logical
Researched · playable - Hard
Backpropagation by Hand
Machine Learning · Neural Networks
Researched · playable - Medium
Bagging: Why Averaging Reduces Variance
Machine Learning · Ensemble Methods
Researched · playable - Easy
Balanced Brackets
Programming · Other
Researched · playableIMC · Topic guidanceOptiver · Topic guidanceHudson River Trading · Topic guidance - Medium
Balancing the Grid
Energy Trading · Energy Sources
Researched · playable - Easy
Bankrupt
Probability and Statistics · Markov Chain Probability
Researched · playable - Medium
Basic (Quadratic) Utility
Asset Pricing · Market Dynamics
Researched · playable - Easy
Basis Point (BP)
Derivatives Theory · ETF Theory
Researched · playable - Medium
Batch, Stochastic and Mini-Batch Gradient Descent
Machine Learning · Optimization
Researched · playable
Catalogue metadata captured 2026-10-12. Metadata source.