Data Sciences Challenges
Explore data science challenges on Ewance to build skills employers expect from analysts and ML engineers. Work through challenges on data cleaning, exploratory analysis, modeling, and storytelling with data.
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- CodeIntermediateNew
Build a CodeQL Query Pack to Catch Logging-of-PII
Use CodeQL to write queries for Java and Python that detect data flow from PII sources (request parameters, database columns marked PII, user-profile fields) into logging sinks …
- Static Analysis
- Codeql
- Data Flow Analysis
Program Analysis - CodeIntermediateNew
Build a Dataflow-Based Dead-Code Detector for a Python Monorepo
Build a Python tool using libcst (or ast + jedi) that constructs a call graph across the monorepo. Account for indirect references (entry points in setup.py / pyproject.toml, dy…
- Dataflow Analysis
- Ast
- Call Graph
Program Analysis - CodeIntermediateNew
Implement a Persistent Immutable List for a Collaborative-Editing Startup
Implement in Python (or TypeScript / Kotlin). Build a persistent immutable list with operations: get, set, append, pop, slice, concat. Use structural sharing (32-way vector trie…
- Data Abstraction
- Recursion
- Persistent Data Structures
Programming Abstractions - DesignIntermediateNew
Design a Small Domain-Specific Language for Invoice Rules
Design a DSL grammar (BNF) covering: boolean conditions (and / or / not), comparison operators, customer-attribute references, line-attribute references, and action expressions …
- Abstraction
- Recursion
- Domain Specific Language
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- CodeIntermediateNew
Bloom Filter Cache to Cut Origin Load at a CDN Edge
Given a target false-positive rate of 1 percent at 200 million keys per shard, compute the optimal bit-array size (m) and hash-function count (k) using the canonical formulas. I…
- Bloom Filters
- Probabilistic Data Structures
- Hash Functions
Randomized Algorithms - CodeIntermediateNew
MinHash Similarity Sketch for a Job-Board Deduplication Pipeline
Implement a MinHash signature generator (128 permutations) over shingled job-posting text (5-gram word shingles). Build an LSH banding index (16 bands of 8 hashes each) tuned fo…
- Minhash
- Locality Sensitive Hashing
- Probabilistic Data Structures
Randomized Algorithms - AnalysisIntermediateNew
Randomized Load Balancer with the Power of Two Choices
Simulate four placement policies on a 24-hour anonymized connection-establishment trace (around 4.1 billion events): (1) random-1, (2) round-robin, (3) P2C with instantaneous lo…
- Power Of Two Choices
- Load Balancing
- Randomized Algorithms
Randomized Algorithms - CodeIntermediateNew
Reservoir Sampling for a Privacy-Preserving Telemetry Pipeline
Implement Vitter's Algorithm R (and the faster Algorithm L for bonus credit) producing a 90M-event uniform sample per day from a stream of 18B. Add per-key stratification (so lo…
- Reservoir Sampling
- Randomized Algorithms
- Streaming Systems
Randomized Algorithms - Browse challenges
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Pricing Strategist
Set the price that captures value without leaving sales on the table. Demand modelling, willingness-to-pay research, and the disciplined experimentation that turns pricing into a competitive advantage.
- StrategyIntermediateNew
Requirements Management for a 2-Year Banking Core Migration
Pick a requirements-management tool (Jama Connect, Polarion, or a Confluence + Jira pattern) and justify the choice against the bank's audit + compliance needs. Define a metamod…
- Requirements Management
- Traceability
- Governance
Requirements Engineering - CodeIntermediateNew
Multi-Tenant Schema Migration for a Series-B HR SaaS
Design a 4-phase migration: (1) add new columns + tables, dual-write on every workflow mutation, (2) backfill 3.4 TB in chunks of around 50k rows per minute with throttling and …
- Multi Tenant Architecture
- Schema Migration
- Dual Write
Engineering Software as a Service - AnalysisIntermediateNew
ODE Integrator Benchmark for a Pharma PK/PD Pipeline
Use SciPy's solve_ivp + SUNDIALS (via scikit-sundae or diffeqpy) to benchmark: RK45 (baseline), LSODA, BDF (CVODE), Radau, and Rosenbrock. Run on three model classes (insulin-gl…
- Numerical Odes
- Stiff Integrators
- Scientific Python
Scientific Computing and Numerical Methods - CodeIntermediateNew
FFT-Based Acoustic Beamforming on Streaming Microphone Arrays
Implement overlap-add streaming FFT (FFTW or KissFFT) processing 64 channels × 1024-sample frames with 50 percent overlap. Apply delay-and-sum beamforming across a 2D direction-…
- Fft
- Signal Processing
- Beamforming
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Why Ewance
- AnalysisIntermediateNew
Capacity Planning Model for a Black-Friday Traffic Surge
Pull 18 months of per-service request rate + utilization from Prometheus. Forecast BFCM traffic per service using a baseline + multiplicative seasonal model (Prophet or statsmod…
- Capacity Planning
- Forecasting
- Autoscaling
Site Reliability Engineering - CodeIntermediateNew
Repository + Unit-of-Work Refactor on an EF Core Codebase
Read the data-access patterns across the 5 bounded contexts (Payroll, Timesheets, Benefits, Org, Reporting) and tag the 12 worst N+1 incidents from the last quarter's traces. Au…
- Repository Pattern
- Unit Of Work
- Design Patterns
Software Design and Design Patterns - AnalysisIntermediateNew
Empirical Study of PR Review Throughput on a Mid-Sized Monorepo
Pull 8 weeks of PR data from the monorepo (~3,800 PRs across 12 teams) covering open-to-merge time, review-comment count, review-round count, reviewer count, lines changed, and …
- Empirical Software Engineering
- Software Analytics
- Statistical Analysis
Advanced Software Engineering - CodeIntermediateNew
Software Analytics Dashboard for an Engineering Org
Author a metric catalog defining each of ~15 metrics with formula, data source, refresh cadence, and known caveats (e.g. lead-time-for-changes excludes WIP-flagged PRs to avoid …
- Software Analytics
- Dora Metrics
- Space Framework
Advanced Software Engineering - ResearchIntermediateNew
Industrial Case Study: Why a Microservices Migration Failed
Conduct 8 1-hour interviews across CTO, 3 tech leads, 2 platform engineers, 1 SRE, and the product VP. Analyze 24 months of artifacts (ADRs, RFCs, incident reports, deployment d…
- Industrial Case Study
- Qualitative Research
- Software Architecture
Advanced Software Engineering - StrategyIntermediateNew
Roll Out an Advanced Process Model (LeSS) to 6 Product Teams
Read the LeSS framework (Larman + Vodde) and audit the 6 teams' current Scrum practice (anonymized data + 4 hours of recorded ceremonies). Author a 10-page rollout design coveri…
- Advanced Process Models
- Scaling Agile
- Less
Advanced Software Engineering - AnalysisIntermediateNew
Reverse-Engineer a 22-Year-Old COBOL Batch Pipeline
Use SonarQube + cobol-language tooling + JCL parsers to extract job dependencies and data-flow across the 140 jobs. Build a job-dependency graph (Graphviz). Run impact analysis:…
- Reverse Engineering
- Legacy Systems
- Dependency Analysis
Software Evolution and Maintenance - AnalysisIntermediateNew
Defect-Trend Analysis and Quality Action Plan for an EV Charging Platform
Pull 18 months of defect data from Jira + the field-incident system + customer-service tickets. Categorize defects by component, severity, and root-cause taxonomy. Run statistic…
- Defect Analysis
- Statistical Process Control
- 5 Whys & Fishbone Root Cause Analysis
Software Quality and Process Improvement - CodeIntermediateNew
Fuzz a Memory-Unsafe Image-Parsing Library
Identify 3 critical parser entry points (DICOM dataset parser, JPEG 2000 decoder, TIFF directory parser) and write a libFuzzer harness + an AFL++ harness for each. Build with AS…
- Fuzzing
- Memory Safety
- Address Sanitizer
Software Security - DesignIntermediateNew
Threat Model a HealthTech Patient-Portal Web App
Read the 25-page redesign architecture document (auth via Clerk, Next.js front-end, FastAPI backend, Postgres, S3 for documents, webhook integration with EMRs). Build data-flow …
- Threat Modeling
- STRIDE
- Secure Design
Software Security - AnalysisIntermediateNew
Mutation Testing on a Critical Pricing Service
Run PIT against the pricing service to get a baseline mutation score per class. Identify the 5 classes with the largest gap between line coverage and mutation score (these are t…
- Mutation Testing
- Python Or Javascript
- Junit
Software Testing and Quality Assurance - CodeIntermediateNew
Multi-Tenant SaaS Backend with Postgres Row Security
Design the multi-tenant schema: shared tables with a tenant_id column, indexed appropriately. Write a forward + backward migration (using Drizzle or Prisma). Implement Postgres …
- Multi Tenant Architecture
- Postgresql Or Mysql
- Row Level Security
Web Application Development
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