6-Week Interview Study Calendar

• OOP pillars; composition vs inheritance
• Collections: ArrayList, HashMap, TreeMap, ConcurrentHashMap
• Generics, wildcards, Optional, records

• Explain HashMap vs TreeMap trade-offs out loud
• Implement a simple LRU cache skeleton (no need to finish)

1.5h — warm-up 5m, problems 55m, review 30m

• Two Sum #1 Easy
• Contains Duplicate #217 Easy
• Valid Anagram #242 Easy

Explore a language, framework, or tool you've wanted to learn.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• ExecutorService, CompletableFuture, synchronized vs volatile
• Streams API: map, filter, reduce, parallel streams
• GC basics: Young/Old gen, memory leak causes

• Explain happens-before with an example
• Sketch producer-consumer with BlockingQueue

1.5h — warm-up 5m, problems 55m, review 30m

• Valid Palindrome #125 Easy
• 3Sum #15 Medium
• Container With Most Water #11 Medium

Explore a language, framework, or tool you've wanted to learn.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• INNER/LEFT JOINs; GROUP BY vs HAVING
• Window functions: ROW_NUMBER, RANK, LAG
• Indexes, EXPLAIN, isolation levels (ACID)

• Write second-highest salary query
• Design schema for orders + order_items + customers

1.5h — warm-up 5m, problems 55m, review 30m

• Best Time to Buy and Sell Stock #121 Easy
• Longest Substring Without Repeating Characters #3 Medium

Explore a language, framework, or tool you've wanted to learn.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• HashMap buckets, load factor, treeification
• Fail-fast vs fail-safe iterators
• SOLID principles with Java examples

• Implement thread-safe singleton two ways
• Explain a concurrency bug involving shared mutable state

1.5h — timed sets, 35 min per problem + review

• Group Anagrams #49 Medium
• Product of Array Except Self #238 Medium

Explore a language, framework, or tool you've wanted to learn.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Normalization vs denormalization for interview schemas
• Python: GIL, list vs tuple; Go: goroutines vs threads
• JavaScript: event loop, closures (light read)

• Normalize a messy e-commerce schema on paper
• Skim JS/Python/Go must-know sections in study guide

1.5h — 3 mixed Easy/Medium from the week

• Best Time to Buy and Sell Stock #121 Easy
• Longest Substring Without Repeating Characters #3 Medium

Explore a language, framework, or tool you've wanted to learn.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• @SpringBootApplication, auto-configuration
• Constructor injection; request lifecycle in MVC
• Actuator health checks and profiles

• Draw request path: filter → controller → service → repo
• List 5 common @Transactional pitfalls

1.5h — warm-up 5m, problems 55m, review 30m

• Reverse Linked List #206 Easy
• Merge Two Sorted Lists #21 Easy

Personal project: set up repo, CI, or first API endpoint.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Filter chain; UserDetailsService, BCrypt
• JWT structure: header.payload.signature
• Stateless auth vs session; CORS/CSRF basics

• Walk through JWT login → validate on each request
• Explain why not to store JWT in localStorage

1.5h — warm-up 5m, problems 55m, review 30m

• Valid Parentheses #20 Easy
• Min Stack #155 Medium

Personal project: set up repo, CI, or first API endpoint.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Entity relationships; LAZY vs EAGER
• N+1 fixes: JOIN FETCH, @EntityGraph
• @Transactional propagation and LazyInitializationException

• Explain N+1 with example SQL output
• Map bidirectional @OneToMany owning side

1.5h — warm-up 5m, problems 55m, review 30m

• Number of Islands #200 Medium

Personal project: set up repo, CI, or first API endpoint.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Mockito when/thenReturn, verify, ArgumentCaptor
• @WebMvcTest vs @SpringBootTest
• REST resources, status codes, idempotency (POST vs PUT)

• Unit test a service with mocked repository
• Design REST API for orders (5 endpoints on paper)

1.5h — warm-up 5m, problems 55m, review 30m

• Search Insert Position #35 Easy
• Find Minimum in Rotated Sorted Array #153 Medium

Personal project: set up repo, CI, or first API endpoint.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Maven lifecycle: compile, test, package
• dependency:tree for conflict resolution
• TypeScript: interfaces vs types, generics (awareness)

• Build CRUD API with validation + global exception handler
• Run mvn dependency:tree on a sample project

1.5h — LL + stack mix, 2 Medium

• Reverse Linked List #206 Easy
• Valid Parentheses #20 Easy
• Min Stack #155 Medium

Personal project: set up repo, CI, or first API endpoint.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Monolith vs microservices trade-offs
• Saga: orchestration vs choreography
• Circuit breaker, retry, timeout, bulkhead

• Draw order → payment → inventory across 3 services
• Explain when NOT to use microservices

1.5h — warm-up 5m, problems 55m, review 30m

• Maximum Depth of Binary Tree #104 Easy
• Invert Binary Tree #226 Easy
• Same Tree #100 Easy

Side experiment: messaging, caching, or a small microservice.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Topics, partitions, offsets, consumer groups
• At-least-once vs exactly-once (conceptual)
• Dead letter topics; event-driven patterns

• Design: order created → payment → notification via Kafka
• Explain consumer lag and rebalance

1.5h — warm-up 5m, problems 55m, review 30m

• Validate Binary Search Tree #98 Medium
• Kth Smallest Element in a BST #230 Medium

Side experiment: messaging, caching, or a small microservice.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Pagination, filtering, versioning, error format
• OpenAPI/Swagger; POST vs PUT vs PATCH
• GraphQL vs REST trade-offs (awareness)

• Design OpenAPI spec for 5–10 endpoints
• Explain when GraphQL is a good fit vs REST

1.5h — warm-up 5m, problems 55m, review 30m

• Binary Tree Level Order Traversal #102 Medium
• Binary Tree Right Side View #199 Medium

Side experiment: messaging, caching, or a small microservice.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Outbox/inbox pattern; idempotent consumers
• Exactly-once vs at-least-once delivery
• CAP/PACELC; eventual consistency examples

• Explain why distributed transactions are hard
• Sketch outbox pattern for order + payment

1.5h — warm-up 5m, problems 55m, review 30m

• Path Sum #112 Easy
• Lowest Common Ancestor of a Binary Tree #236 Medium

Side experiment: messaging, caching, or a small microservice.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Strategy vs Factory; Repository with Spring Data
• Circuit Breaker, Saga, Outbox (distributed patterns)
• SOLID — explain each with example

• Refactor a if/else chain to Strategy pattern on paper
• List enterprise patterns: DTO, Service Layer, Unit of Work

1.5h — warm-up 5m, problems 55m, review 30m

• Clone Graph #133 Medium
• Course Schedule #207 Medium

Side experiment: messaging, caching, or a small microservice.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• EC2: security groups, ASG, public vs private subnets
• S3: storage classes, pre-signed URLs, versioning
• RDS: Multi-AZ, read replicas; Lambda triggers

• Draw 3-tier app: ALB → EC2 → RDS
• Compare Lambda vs EC2 vs containers for a use case

1.5h — warm-up 5m, problems 55m, review 30m

• Number of Provinces #547 Medium
• Pacific Atlantic Water Flow #417 Medium

Personal project: Dockerize and deploy to cloud/local K8s.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• VPC: CIDR, subnets, IGW, NAT gateway
• IAM: roles, policies, least privilege
• EKS: control plane, Deployments, Services, Ingress, IRSA

• Design highly available app on AWS (multi-AZ)
• Explain IRSA for pod-level AWS permissions

1.5h — warm-up 5m, problems 55m, review 30m

• Kth Largest Element in an Array #215 Medium
• Top K Frequent Elements #347 Medium

Personal project: Dockerize and deploy to cloud/local K8s.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Images vs containers; layer caching
• Multi-stage builds for Java/Spring
• Docker Compose for local PostgreSQL + Kafka

• Write Dockerfile for Spring Boot (non-root user)
• Debug a container that exits immediately

1.5h — warm-up 5m, problems 55m, review 30m

• Word Ladder #127 Hard
• Network Delay Time #743 Medium

Personal project: Dockerize and deploy to cloud/local K8s.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Pods, Deployments, Services, ConfigMaps, Secrets
• Liveness/readiness probes; rolling updates
• Helm charts: values.yaml, install/upgrade/rollback

• Deploy Spring Boot with Deployment + Service + Ingress
• Explain Helm vs raw kubectl vs Kustomize

1.5h — warm-up 5m, problems 55m, review 30m

• Merge k Sorted Lists #23 Hard

Personal project: Dockerize and deploy to cloud/local K8s.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Pipeline: build → test → scan → deploy
• Terraform state, modules, plan/apply
• Logs, metrics, traces; SLI/SLO; RED/USE metrics

• Sketch GitHub Actions pipeline for Java → EKS
• List golden signals for a REST API

1.5h — 2 review problems (graph + heap)

• Number of Provinces #547 Medium
• Course Schedule #207 Medium
• Top K Frequent Elements #347 Medium

Personal project: Dockerize and deploy to cloud/local K8s.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Authorization Code + PKCE for SPAs
• Roles: Auth Server, Resource Server, Client
• Scopes and least privilege

• Draw full login flow for web app
• Explain machine-to-machine client credentials

1.5h — warm-up 5m, problems 55m, review 30m

• Climbing Stairs #70 Easy
• House Robber #198 Medium

Frontend polish or a feature you've been putting off.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• JWT validation: signature, exp, iss, audience
• SAML vs OIDC — enterprise SSO
• RBAC vs ABAC; AWS IAM roles and policies

• Design roles for admin/user/support
• Explain refresh token rotation

1.5h — warm-up 5m, problems 55m, review 30m

• Unique Paths #62 Medium
• Minimum Path Sum #64 Medium

Frontend polish or a feature you've been putting off.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• useState, useEffect, useMemo, useCallback pitfalls
• Controlled forms; Context vs prop drilling
• Strict typing for props and API responses

• Build paginated user list consuming Spring API (sketch)
• Explain reconciliation / virtual DOM at high level

1.5h — warm-up 5m, problems 55m, review 30m

• Jump Game #55 Medium
• Non-overlapping Intervals #435 Medium

Frontend polish or a feature you've been putting off.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• App Router; Server vs Client Components
• SSR vs SSG vs ISR; JWT in httpOnly cookie
• PG: MVCC, EXPLAIN; MySQL: InnoDB, replication

• Outline Next.js app with loading/error states
• Optimize a slow query with EXPLAIN ANALYZE

1.5h — warm-up 5m, problems 55m, review 30m

• Subsets #78 Medium
• Combination Sum #39 Medium

Frontend polish or a feature you've been putting off.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• ES: inverted index, query DSL; vs SQL for search
• RabbitMQ vs Kafka; WebSocket vs SSE
• ETL batch vs stream; GCP ↔ AWS equivalents

• Design ES mapping for product catalog search
• Skim GCP, ETL, RabbitMQ must-know in study guide

1.5h — warm-up 5m, problems 55m, review 30m

• Coin Change #322 Medium
• Longest Increasing Subsequence #300 Medium

Frontend polish or a feature you've been putting off.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Clarify requirements → estimate QPS/storage
• Load balancer → API → cache → DB → queue
• URL shortener: hashing, collision, redirect flow

• 45-min timed URL shortener on whiteboard
• List trade-offs explicitly for each choice

1.5h — 1 Medium timed (40m) + review

• Group Anagrams #49 Medium
• Number of Islands #200 Medium

Portfolio project: README, demo, and interview talking points.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Order, Payment, Inventory services
• Kafka events; PostgreSQL per service; Redis cache
• React frontend; OAuth2/JWT; observability

• Draw full-stack e-commerce architecture end-to-end
• Walk through CORE_DOMAINS A–G out loud (30 min each)

1.5h — 1 Medium from weak spots + review

• Binary Tree Level Order Traversal #102 Medium
• Course Schedule #207 Medium

Portfolio project: README, demo, and interview talking points.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Run through REVISION_CHECKLIST items 1–7
• Explain HashMap, @Transactional, N+1, REST idempotency
• Draw VPC app with ALB, EKS, RDS, S3

• Record yourself answering 3 checklist questions (5 min each)
• Fix gaps using study guide must-know sections

1.5h — 1 Easy warm-up + 1 Medium

• Two Sum #1 Easy
• Validate Binary Search Tree #98 Medium
• House Robber #198 Medium

Portfolio project: README, demo, and interview talking points.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Mock: 45 min system design + 15 min Q&A
• Behavioral: STAR stories for conflict, failure, leadership
• Review CI/CD, Security, System design checklist items 8–13

• Mock with a friend or record solo (notification system design)
• Prepare 3 STAR stories for common behavioral questions

1.5h — 1–2 problems from your mistake log

• 3Sum #15 Medium
• Merge k Sorted Lists #23 Hard

Portfolio project: README, demo, and interview talking points.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda

• Complete full REVISION_CHECKLIST (all 13 areas)
• Outline one portfolio project using full core stack
• Review hands-on callout: end-to-end stack project

• Write 1-page architecture doc for portfolio project
• Schedule real interviews or apply to 3 target jobs

1.5h — 1 Medium, no hints, interview conditions

• Product of Array Except Self #238 Medium
• Coin Change #322 Medium

Portfolio project: README, demo, and interview talking points.

• Study topics you're personally interested in (outside the guide)
• Work on a personal or portfolio project
• Read docs, tutorials, or experiment freely — no fixed agenda