Showing posts with label Architecture. Show all posts
Showing posts with label Architecture. Show all posts

20 October 2026

# API Gateway Pattern

Key Concepts


S.NoTopicSub Topic
1 API Gateway Fundamentals API Gateway purpose, request lifecycle, gateway vs reverse proxy, gateway vs load balancer
2 Spring Cloud Gateway Route configuration, predicates, filters, GlobalFilter, GatewayFilter, route ordering
3 Request Routing Path-based routing, header-based routing, host-based routing, method-based routing, query parameter routing
4 Custom Filters Pre-filter, post-filter, custom GlobalFilter, filter ordering, request and response modification
5 Authentication OAuth 2.0, OpenID Connect, JWT validation, API key authentication, token introspection
6 Authorization Role-based access control, scope-based authorization, claims validation, route-level access control
7 Spring Security Integration SecurityWebFilterChain, JWT resource server, authentication context, public and protected routes
8 Token Propagation Token Relay, forwarding access tokens, downstream authentication, service-to-service credentials
9 Rate Limiting Redis rate limiter, token bucket, per-user limits, per-client limits, per-IP limits, HTTP 429
10 Load Balancing Spring Cloud LoadBalancer, service instance selection, round robin, health-aware routing
11 Service Discovery Eureka integration, dynamic service registration, discovery locator, service discovery in Kubernetes
12 Resilience and Circuit Breaker Resilience4j, circuit breaker states, fallback responses, failure isolation, cascading failure prevention
13 Timeout Management Connection timeout, response timeout, downstream timeout, end-to-end timeout budgeting
14 Retry Handling Retry filters, retryable status codes, exponential backoff, idempotency, duplicate request prevention
15 Error Handling 401 vs 403, 404 route mismatch, 502 bad gateway, 503 service unavailable, 504 gateway timeout, standardized error responses
16 CORS Configuration Allowed origins, allowed methods, allowed headers, credentials, preflight requests, duplicate CORS headers
17 Request and Response Transformation Header manipulation, path rewriting, request body modification, response header modification, query parameter changes
18 API Versioning URI versioning, header versioning, version-based routing, backward compatibility, API deprecation
19 Observability and Logging Structured logging, correlation ID, request tracing, access logs, latency metrics, error-rate monitoring
20 Distributed Tracing OpenTelemetry, Micrometer Tracing, trace ID propagation, span creation, downstream trace correlation
21 Performance Optimization Connection pooling, keep-alive, non-blocking I/O, reactive programming, payload compression, memory optimization
22 Caching HTTP caching, Cache-Control, ETag, Redis caching, cache key design, cache invalidation
23 Security Hardening TLS termination, mutual TLS, certificate management, IP allowlisting, request size limits, sensitive header sanitization
24 API Documentation OpenAPI, Swagger UI, API specifications, route documentation, consumer onboarding
25 Testing Unit testing filters, integration testing, WireMock, contract testing, load testing, security testing
26 Configuration Management Externalized configuration, environment profiles, route configuration, secret management, configuration rollback
27 Kubernetes Deployment Gateway replicas, readiness probes, liveness probes, horizontal scaling, graceful shutdown, Kubernetes Gateway API
28 High Availability Active-active deployment, health checks, failover, multi-zone deployment, disaster recovery, capacity planning
29 Production Troubleshooting 401/403 errors, 404 routing issues, 429 throttling, 502/503/504 errors, DNS failures, TLS handshake issues
30 Architecture Design and Trade-offs API Gateway vs service mesh, BFF pattern, gateway aggregation, centralized policies, avoiding business logic in the gateway

Interview Question



What is the API Gateway Pattern, and why is it used in microservices architecture?
What are the primary responsibilities of an API Gateway?
What is the difference between an API Gateway and a reverse proxy?
What is the difference between an API Gateway and a load balancer?
What is the difference between an API Gateway and a service mesh?
How does a request flow through Spring Cloud Gateway?
What are routes, predicates, and filters in Spring Cloud Gateway?
What is the difference between GatewayFilter and GlobalFilter?
How do you configure routes in Spring Cloud Gateway?
How do you implement a custom GlobalFilter?
How does filter ordering work in Spring Cloud Gateway?
How do you route requests based on paths, headers, hosts, and HTTP methods?
How do you rewrite request paths before forwarding them to a microservice?
What is the difference between StripPrefix and RewritePath?
How do you route requests dynamically using service discovery?
How do you integrate Spring Cloud Gateway with Eureka?
How does load balancing work with Spring Cloud Gateway?
What is the difference between static routing and service-discovery-based routing?
How do you implement API versioning through an API Gateway?
How do you implement canary routing using Spring Cloud Gateway?
How do you secure an API Gateway using Spring Security?
How do you configure JWT authentication in Spring Cloud Gateway?
Which JWT claims should be validated by an API Gateway?
What is the difference between OAuth 2.0 and OpenID Connect?
How do you implement role-based authorization at the gateway?
What is token relay, and how is it implemented in Spring Cloud Gateway?
How do you propagate authentication information to downstream microservices?
Why should microservices enforce authorization even when the gateway authenticates requests?
How do you implement API key authentication, and what are its limitations?
How do you configure CORS in Spring Cloud Gateway?
What is rate limiting, and why is it important for an API Gateway?
How do you implement Redis-based rate limiting in Spring Cloud Gateway?
How does the token-bucket algorithm work?
How do you implement different rate limits for different users and clients?
How do you enforce rate limits across multiple gateway instances?
What is the difference between rate limiting and throttling?
How should an API Gateway handle requests that exceed rate limits?
How do you configure connection and response timeouts for downstream services?
What is a circuit breaker, and how do you configure it for gateway routes?
How do you integrate Resilience4j with Spring Cloud Gateway?
What is the difference between a timeout, retry, circuit breaker, and fallback?
How do you configure retries without creating duplicate transactions?
Why should retries use exponential backoff and jitter?
How do you prevent cascading failures across microservices?
How do you implement fallback responses when a downstream service is unavailable?
How do you handle HTTP 401, 403, 404, 429, 502, 503, and 504 responses?
How do you standardize error responses returned by the gateway?
How do you implement request and response header transformation?
How do you validate incoming requests and restrict payload sizes?
How do you prevent clients from spoofing identity and forwarded headers?
How do you configure TLS termination at an API Gateway?
What is mutual TLS, and when should it be used?
How do you manage certificates and secrets securely for gateway deployments?
How do you implement correlation IDs across gateway and microservice requests?
How do you integrate OpenTelemetry and Micrometer Tracing with Spring Cloud Gateway?
How do you monitor gateway latency, throughput, error rates, and saturation?
Why are p95 and p99 latency metrics important for gateway monitoring?
How do you troubleshoot a 502 Bad Gateway error in production?
How do you troubleshoot a 504 Gateway Timeout error?
How do you investigate high latency when downstream services appear healthy?
How do you configure structured logging without exposing tokens or sensitive data?
How does reactive programming improve API Gateway scalability?
Why should blocking operations be avoided in Spring Cloud Gateway's reactive event loop?
How do you identify and resolve memory pressure and connection-pool exhaustion?
How do you configure connection pooling and keep-alive for gateway traffic?
What is backpressure, and why is it important in reactive gateway applications?
How do you implement response caching at an API Gateway?
How do you handle cache invalidation and prevent stale responses?
When should gateway caching be avoided for sensitive or user-specific data?
What is the Backend for Frontend pattern, and when should it be used?
What is gateway aggregation, and how do you handle parallel downstream calls?
When should aggregation logic be moved from the gateway into a dedicated service?
How do you prevent one slow downstream call from delaying an aggregated response?
What is the Strangler Pattern, and how can a gateway support legacy modernization?
How do you integrate API Gateway with Kafka-based asynchronous microservices?
How do you route WebSocket connections through an API Gateway?
How do you document gateway routes using OpenAPI and Swagger?
How do you test route predicates and custom filters using Spring Boot tests?
How do you use WireMock to test gateway behavior when downstream services fail?
How do you perform load testing and stress testing for an API Gateway?
How do you deploy Spring Cloud Gateway to Kubernetes?
What is the difference between Kubernetes Ingress and Gateway API?
How do you configure readiness and liveness probes for gateway instances?
How do you achieve high availability using multiple gateway replicas?
How do you deploy gateway configuration changes without downtime?
How do you implement blue-green and canary deployments for gateway services?
How do you manage gateway routes and environment-specific configuration?
How do you prevent invalid route configuration from breaking production traffic?
How do you implement graceful shutdown while preserving in-flight requests?
How do you implement tenant-aware routing and per-tenant authorization?
How do you isolate one tenant's traffic from other tenants?
How do you design an API Gateway for banking or payment microservices?
How do you prevent duplicate payment requests when the gateway experiences timeouts?
How do you secure public APIs against abuse, oversized payloads, and malicious requests?
How do you design regional routing and failover for a multi-region gateway?
How do you estimate API Gateway capacity based on requests per second and latency?
How do you determine whether the API Gateway itself has become a performance bottleneck?
What are the most common API Gateway anti-patterns in microservices architecture?
How do you decide which responsibilities belong in the gateway versus individual microservices?
How would you design a production-ready Spring Cloud Gateway architecture with security, resilience, observability, and high availability?
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26 August 2026

#System design


Key Concepts


S.No Topic Sub-Topics
1 System Design  Functional vs Non-Functional Requirements, Scalability, Availability & Reliability, Latency & Throughput, CAP Theorem, Consistency Models, Trade-offs
2 Requirements & Capacity Estimation Functional Requirements, Non-Functional Requirements, QPS Estimation, Storage Estimation, Bandwidth Estimation, Traffic Estimation, Back-of-the-Envelope Calculations
3 API & Interface Design REST APIs, gRPC, API Versioning, Idempotency, Authentication & Authorization, Rate Limiting, Request Validation
4 Networking HTTP/HTTPS, DNS, TCP/IP, Load Balancers, CDN, Firewall & NAT, Timeouts & Keep-Alive
5 High-Level Design (HLD) Component Diagram, Data Flow Diagram, Service Boundaries, Microservices, Database Selection, Scalability, Bottleneck Identification
6 Low-Level Design (LLD) SOLID Principles, Design Patterns, Class Diagrams, Sequence Diagrams, Object-Oriented Design, API & Component Design, Extensibility
7 Databases SQL vs NoSQL, Indexing, Normalization, Sharding, Replication, Partitioning, ACID vs BASE
8 Caching Why Caching, Cache-Aside, Write-Through, Write-Behind, TTL, LRU/LFU, Cache Invalidation
9 Scalability Vertical vs Horizontal Scaling, Auto Scaling, Stateless Services, Service Discovery, Load Balancing, Database Scaling, Partitioning
10 Storage Systems Object Storage, Block Storage, File Storage, Data Lakes, Log Aggregation, Backup & Recovery, Hot vs Cold Storage
11 Distributed Systems Consistency Models, Strong vs Eventual Consistency, Distributed Transactions, 2PC/3PC, Saga Pattern, Consensus, Leader Election
12 Messaging & Event-Driven Systems Kafka, RabbitMQ, SQS, Pub/Sub, Event Streaming, Sync vs Async Communication, Delivery Semantics
13 Fault Tolerance & Resilience Retry, Timeout, Circuit Breaker, Bulkhead, Rate Limiting, Failover, Graceful Degradation
14 Security OAuth 2.0, JWT, RBAC/ACL, TLS/SSL, Encryption at Rest & In Transit, Secrets Management, OWASP Basics
15 Observability Logging, Metrics, Distributed Tracing, Monitoring, Alerting, SLI/SLO/SLA, Dashboards
16 DevOps & Deployment CI/CD, Docker, Kubernetes, Blue-Green Deployment, Canary Deployment, Infrastructure as Code, GitOps
17 Social Media System Design Feed Generation, Fan-out, Timeline Service, Follow Graph, Caching, Sharding, Real-time Notifications
18 E-Commerce System Design Product Catalog, Cart, Order Service, Inventory, Payment, Search, Event-Driven Architecture
19 Ride-Hailing System Design Geospatial Queries, Location Tracking, Driver Matching, Trip Management, Real-time Events, Surge Pricing, Scalability
20 Video Streaming System Design Video Upload, Transcoding, Object Storage, CDN, Metadata, Streaming, Content Delivery
21 Banking & Payment System Design Payment Gateway, Transaction Processing, Ledger, Idempotency, Fraud Detection, Distributed Transactions, Disaster Recovery
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16 September 2025

#Microservice


Key Concepts


# Microservices Concept Description Pattern
1 Microservice Small, independently deployable business service Decomposition Pattern
2 Service Decomposition Break application into smaller business services Decompose by Business Capability
3 API Gateway Single entry point for client requests API Gateway Pattern
4 Service Discovery Dynamically finds available service instances Service Discovery Pattern
5 Load Balancing Distributes requests across service instances Load Balancer Pattern
6 Service Communication Enables communication between services Remote Procedure Call Pattern
7 Asynchronous Communication Services communicate without waiting for response Messaging Pattern
8 Event-Driven Architecture Services communicate through business events Event-Driven Pattern
9 Database per Service Each service owns its data Database-per-Service Pattern
10 Shared Database Multiple services share a database Shared Database Pattern
11 Distributed Transaction Transaction spans multiple services Distributed Transaction Pattern
12 Saga Manages transactions across multiple services Saga Pattern
13 Saga Choreography Services coordinate through events Choreography Pattern
14 Saga Orchestration Central coordinator manages the workflow Orchestration Pattern
15 Circuit Breaker Prevents repeated calls to failing services Circuit Breaker Pattern
16 Retry Reattempts failed operations Retry Pattern
17 Timeout Stops calls that take too long Timeout Pattern
18 Bulkhead Isolates failures between services Bulkhead Pattern
19 Fallback Provides alternative behavior when a service fails Fallback Pattern
20 Rate Limiting Controls the number of incoming requests Rate Limiting Pattern
21 Caching Stores frequently accessed data for faster retrieval Cache-Aside Pattern
22 CQRS Separates read and write operations CQRS Pattern
23 Event Sourcing Stores state changes as a sequence of events Event Sourcing Pattern
24 Idempotency Ensures repeated requests don't create duplicate effects Idempotency Pattern
25 Strangler Fig Gradually replaces a legacy application Strangler Fig Pattern
26 Anti-Corruption Layer Protects a new service from legacy models Anti-Corruption Layer Pattern
27 Backend for Frontend Provides a dedicated backend for each client BFF Pattern
28 Aggregator Combines responses from multiple services Aggregator Pattern
29 Adapter Converts one interface into another Adapter Pattern
30 Sidecar Runs supporting functionality alongside a service Sidecar Pattern
31 Service Mesh Manages service-to-service communication Service Mesh Pattern
32 Ambassador Handles external communication through a proxy Ambassador Pattern
33 Externalized Configuration Keeps configuration outside application code External Configuration Pattern
34 Centralized Configuration Provides configuration from a central location Configuration Server Pattern
35 Health Check Determines whether a service is operational Health Check Pattern
36 Distributed Tracing Tracks requests across multiple services Distributed Tracing Pattern
37 Centralized Logging Collects logs from multiple services Centralized Logging Pattern
38 Observability Provides visibility into distributed system behavior Observability Pattern
39 Contract Testing Validates compatibility between service consumers and providers Consumer-Driven Contract Pattern
40 API Versioning Allows APIs to evolve without breaking clients API Versioning Pattern
41 Authentication Verifies the identity of users or services Authentication Pattern
42 Authorization Controls access to resources Authorization Pattern
43 Token Propagation Passes user/service identity between services Token Propagation Pattern
44 Zero Trust Services are not automatically trusted Zero Trust Pattern
45 Blue-Green Deployment Uses two environments for safer releases Blue-Green Pattern
46 Canary Deployment Releases changes gradually Canary Release Pattern
47 Rolling Deployment Gradually replaces old service instances Rolling Update Pattern
48 Horizontal Scaling Adds additional service instances Scale-Out Pattern
49 Fault Isolation Prevents one service failure from spreading Failure Isolation Pattern
50 Independent Deployment Allows services to be deployed separately Independent Deployment Pattern

Interview Question



What are Microservices, and how do they differ from Monolithic architecture?
Why are Microservices important for AI and Agentic AI platforms?
What are the core principles of Microservices architecture?
What are the advantages and disadvantages of Microservices?
How do you identify service boundaries in a Microservices architecture?
What is Domain-Driven Design (DDD), and how does it help Microservices?
What is a bounded context in Microservices?
How do you decompose a monolithic application into Microservices?
What are the common communication patterns between Microservices?
How do synchronous and asynchronous communication differ in Microservices?
What is REST-based communication in Microservices?
What is gRPC, and when would you use it in Microservices?
What is event-driven architecture in Microservices?
How do Kafka and Microservices work together in AI systems?
What is an API Gateway, and why is it needed in Microservices?
How do API Gateways support AI and LLM-based applications?
What is service discovery, and how does it work?
How do Eureka, Consul, and Kubernetes Service Discovery differ?
What is client-side vs server-side service discovery?
How do Microservices handle dynamic scaling?
What is centralized configuration management in Microservices?
How does Spring Cloud Config help Microservices?
What is distributed tracing, and why is it important?
How do OpenTelemetry and Zipkin help Microservices observability?
What metrics should be monitored in Microservices?
How do logs, metrics, and traces work together?
What is the role of Prometheus and Grafana in Microservices?
How do you monitor AI service latency in Microservices?
What is resiliency in Microservices?
How do Circuit Breakers work in Microservices?
How does Resilience4j improve fault tolerance?
What are retries, bulkheads, and rate limiters?
How do you prevent cascading failures in Microservices?
How do you design highly available Microservices?
What is eventual consistency in Microservices?
How do SAGA patterns work in distributed transactions?
What is choreography vs orchestration in SAGA?
How do Microservices manage distributed data?
Why should each Microservice own its database?
How do you implement CQRS in Microservices?
What is Event Sourcing, and when should it be used?
How do Microservices support AI data pipelines?
How do Microservices integrate with Vector Databases?
How do Microservices integrate with RAG architectures?
What is an AI Gateway in an LLM platform?
How do you design a Chatbot using Microservices?
How do you design an Agentic AI platform using Microservices?
What Microservices are typically required in an AI platform?
How do Prompt Services fit into a Microservices architecture?
How do Memory Services fit into an Agentic AI architecture?
How do Tool Services fit into Agentic AI platforms?
How do RAG Services fit into AI architectures?
How do Model Routing Services work in AI platforms?
How do Guardrail Services improve AI safety?
How do Evaluation Services measure AI quality?
How do AI Observability Services work?
How do Microservices integrate with OpenAI APIs?
How do Microservices integrate with Azure OpenAI?
How do you manage multiple LLM providers in Microservices?
How do you implement model fallback strategies?
How do you implement AI cost optimization in Microservices?
How do you track token consumption across services?
How do Redis and Microservices work together?
How does Elasticsearch support Microservices?
How does PostgreSQL support Microservices?
How do MongoDB and Microservices work together?
How do Docker and Microservices work together?
How does Kubernetes manage Microservices?
What are Kubernetes Deployments, Services, and Ingress?
How does Horizontal Pod Autoscaling work?
How do Microservices support multi-region deployments?
How do you secure Microservices using OAuth2?
How do JWT tokens work in Microservices?
How do API Gateways enforce security?
How do you implement zero-trust security in Microservices?
How do service-to-service authentication mechanisms work?
How do you secure AI tools exposed through Microservices?
How do you prevent prompt injection from propagating across services?
How do you protect sensitive data in AI Microservices?
How do you implement PII masking across Microservices?
How do you test Microservices independently?
How do contract tests work in Microservices?
How do integration tests work across Microservices?
How do you mock dependent services during testing?
How do you perform performance testing in Microservices?
How do you perform chaos engineering in Microservices?
How do CI/CD pipelines support Microservices?
How do GitOps practices improve Microservices deployments?
How do Blue-Green deployments work?
How do Canary deployments work?
How do Feature Flags help Microservices releases?
How do you troubleshoot production issues in Microservices?
How do you optimize latency in distributed Microservices?
How do you handle high-throughput event processing?
How do you design a scalable enterprise AI platform using Microservices?
How would you design a production-grade RAG platform using Microservices?
How would you design a multi-agent AI platform using Microservices?
How would you design a global-scale AI and LLM platform using Microservices?
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03 September 2025

#DSA

#DSA

Key Concepts


S.No Topic Sub-Topics
1Introduction & ComplexityWhat is DSA, Time Complexity (Big-O), Space Complexity, Best/Average/Worst case, Simple examples
2Arrays BasicsDeclaration & Access, Common operations, Two-pointer technique, Sliding window intro, In-place vs extra space
3Arrays ProblemsSubarray sum, Prefix sums, Kadane's algorithm, Rearrange problems, Dutch National Flag
4Strings BasicsImmutability, Common operations, Character arrays, String builders, Unicode & encodings
5Strings AlgorithmsPattern search (KMP), Rabin-Karp, Anagrams, Palindromes, Trie intro
6Linked ListsSingly vs Doubly, Operations (insert/delete), Reverse list, Fast/Slow pointers, Detect cycle
7Stacks & QueuesLIFO vs FIFO, Implementation using arrays/linked list, Monotonic stack, Circular queue, Applications
8Recursion & BacktrackingRecurrence relations, Call stack, Backtracking patterns, Subset/permutation generation, N-Queens
9Sorting AlgorithmsBubble, Selection, Insertion, Merge sort, Quick sort
10Searching AlgorithmsLinear search, Binary search, Binary search on answer, Search in rotated array, Interpolation search
11Hashing & Hash TablesHash functions, Collision resolution, HashMap/HashSet, Frequency maps, Anagram/counting problems
12Priority Queue & HeapsBinary heap, Insert/extract, Heapify, Kth largest, Heap for merge/k-way
13Trees BasicsBinary tree, Tree traversal (pre/in/post), Height/depth, Recursive vs iterative, Tree representations
14Binary Search Tree (BST)BST properties, Insert/Delete/Search, Lowest common ancestor, Range queries, Balanced vs unbalanced
15Tries (Prefix Trees)Insert/Search, Prefix queries, Autocomplete, Word dictionary, Memory considerations
16Graphs BasicsDirected vs undirected, Adjacency list/matrix, Graph traversal, Connected components, Dense vs sparse
17Graph TraversalBFS, DFS, Tree vs graph traversal, Level order, Parent/Distance tracking
18Shortest Path AlgorithmsDijkstra, Bellman-Ford, SPFA, Weighted vs unweighted, Single-source vs all-pairs
19Minimum Spanning TreeKruskal, Prim, Union-Find intro, Cycle detection, Applications
20Union-Find / Disjoint SetMake/Find/Union, Path compression, Union by rank, Connected components, Offline queries
21Dynamic ProgrammingOverlapping subproblems, Optimal substructure, Memoization vs tabulation, State definition, Simple examples
22Common DP Patterns0/1 Knapsack, Unbounded knapsack, Longest Increasing Subsequence, Longest Common Subsequence, DP on strings
23Advanced DPBitmask DP, DP on trees, Digit DP, Convex hull trick intro, Optimization techniques
24Greedy AlgorithmsGreedy choice property, Activity selection, Huffman coding, Fractional knapsack, Interval scheduling
25Bit ManipulationBit ops (&,|,^,~,<<,>>), Count bits, Lowbit, Bitmask tricks, XOR properties
26Sliding Window & Two PointersFixed window, Variable window, Two-pointer for pairs, Subarray problems, Window optimization
27Prefix/Suffix & Difference ArraysPrefix sums, Suffix sums, Prefix max/min, Range update via diff array, Prefix product
28Segment Tree & Fenwick TreePoint update & range query, Range update & point query, Lazy propagation, Fenwick implementation, Use-cases
29Advanced Graphs & FlowsTopological sort, DAG applications, Max flow (Edmonds-Karp), Min-cut, Matching basics
30Interview Prep & PracticeCommon patterns, Problem-solving checklist, Mock interviews, Platforms (LeetCode, Codeforces), Time-boxed practice

Interview question

Basic Level

  1. What is an algorithm?
  2. Explain Time Complexity and Big-O notation.
  3. What is Space Complexity?
  4. What is an Array?
  5. Difference between Array and Linked List?
  6. What is a Linked List? Types?
  7. What is a Stack? Explain operations.
  8. What is a Queue? Explain types.
  9. Explain postfix, prefix, infix notations.
  10. What is a Hash table?
  11. What is a Tree data structure?
  12. Difference between Binary Tree and Binary Search Tree (BST)?
  13. What is a Graph?
  14. Difference between DFS and BFS.
  15. What is Recursion?
  16. What is Divide and Conquer approach?
  17. Explain Bubble Sort algorithm.
  18. Explain Selection Sort algorithm.
  19. Explain Insertion Sort algorithm.
  20. What is Linear Search?
  21. What is Binary Search?
  22. What is Dynamic Programming (basic definition)?
  23. What is Greedy Algorithm?
  24. What is a Heap?
  25. What is a Hash collision?

Intermediate Level

  1. Explain Merge Sort algorithm and its complexity.
  2. Explain Quick Sort and its complexity.
  3. Explain Two-pointer technique with examples.
  4. Explain Sliding Window technique.
  5. What is Prefix Sum and where is it used?
  6. Explain Kadane?s algorithm.
  7. What is a Circular Linked List?
  8. How do you detect a cycle in a Linked List?
  9. What is a Doubly Linked List?
  10. What is a Priority Queue?
  11. How do you implement a Queue using Stacks?
  12. How do you implement a Stack using Queues?
  13. What is a Trie data structure?
  14. Difference between Tree and Graph.
  15. What is a Balanced Binary Tree?
  16. What is AVL Tree?
  17. What is Red-Black Tree?
  18. Explain Dijkstra?s algorithm.
  19. What is Bellman-Ford algorithm?
  20. Explain Floyd-Warshall algorithm.
  21. What is Kruskal?s algorithm?
  22. What is Prim?s algorithm?
  23. What is Union-Find data structure?
  24. What is Topological Sorting?
  25. What is Backtracking? Give example.

Advanced Level

  1. Explain Segment Tree and its operations.
  2. What is a Fenwick Tree (Binary Indexed Tree)?
  3. Difference between Segment Tree and Fenwick Tree.
  4. Solve: Maximum product subarray.
  5. Solve: Longest increasing subsequence.
  6. Explain Longest Common Subsequence.
  7. What is KMP algorithm?
  8. Explain Rabin-Karp algorithm.
  9. Explain the concept of rolling hash.
  10. What is a Min-Cut and Max-Flow problem?
  11. Explain Edmonds-Karp Algorithm.
  12. Explain Kahn?s algorithm.
  13. Explain A* search algorithm.
  14. What is NP, NP-hard, and NP-complete?
  15. Explain Traveling Salesman Problem.
  16. Explain Bitmask DP with example.
  17. Explain DP on trees.
  18. Explain DP on graphs.
  19. How does binary lifting work?
  20. What is a Sparse Table?
  21. Explain Lowest Common Ancestor problem.
  22. Implement LRU Cache logic.
  23. What is a Bloom Filter?
  24. Explain Consistent Hashing.
  25. Explain Suffix array and Suffix tree.

Expert Level

  1. Solve: Maximum subarray sum for circular array.
  2. Solve: Median of two sorted arrays (log approach).
  3. Solve: Find Kth smallest element in sorted matrix.
  4. Solve: Word ladder shortest path.
  5. Solve: N-Queens problem optimized solution.
  6. Solve: Shortest path in a maze using BFS.
  7. Solve: Course schedule (detect cycle in graph).
  8. Solve: Clone graph problem.
  9. Solve: Regular expression matching (DP).
  10. Solve: Edit distance problem (DP).
  11. Solve: Palindromic subsequence count (DP).
  12. Solve: Max rectangle in binary matrix.
  13. Solve: Largest histogram rectangle.
  14. Solve: Minimum window substring problem.
  15. Solve: Coin change problem variants.
  16. Solve: Sliding window maximum problem.
  17. Solve: Find bridges and articulation points.
  18. Solve: Euler path/circuit check.
  19. Solve: Detect negative cycle in graph.
  20. Solve: Longest path in DAG.
  21. Solve: Kth smallest element using order-statistic tree.
  22. Solve: Streaming median problem.
  23. Solve: Top K frequent elements problem.
  24. Solve: Find strongly connected components (Kosaraju).
  25. Solve: Implement efficient autocomplete system using Trie.

Related Topics


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