Roadmap3 Months Roadmap
CodeSimulators · Roadmaps

Your Day-by-Day
Interview Roadmap

Mixed disciplines every week: 2 days DSA · 2 days LLD · 2 days HLD · 1 revision. Problems progress from easy → medium → hard. Start a roadmap, mark days as you go.

84 Days · 12 Weeks · Balanced prep — every pattern, all LLD systems, full HLD arc
84Total Days
116DSA Problems
70LLD Topics
42HLD Chapters
18Revision Days
DSA Difficulty
● Easy · 27● Medium · 63● Hard · 26
Day Focus
2 DSA Days
2 LLD Days
2 HLD Days
1 Revision Day
Pattern Guide
Week 1Arrays (easy) & Linked Lists intro → OOP Basics → Monolith
Day 1DSA

DSA — Arrays: intuition + easy problems

Arrays & Strings — Pattern GuideDSATwo SumEDSAArray TraversalEDSAMajority ElementEDSAMax Consecutive OnesE
Day 2DSA

DSA — Arrays medium + Linked List intro

DSAMaximum SubarrayMDSAProduct of Array Except SelfMLinked Lists — Pattern GuideDSAReverse Linked ListEDSAMiddle of Linked ListE
Day 3LLD

LLD — Classes, Objects & Encapsulation

LLDClasses & ObjectsLLDEncapsulationLLDAbstraction
Day 4LLD

LLD — Inheritance, Polymorphism & Relationships

LLDInheritanceLLDPolymorphismLLDRelationships
Day 5HLD

HLD — The Monolith

HLDCh 01 — The Monolith
Day 6HLD

HLD — Separate the Database

HLDCh 02 — Separate the Database
Day 7Revision

Revision — Week 1

DSATwo Sum (revisit)EDSAReverse Linked List (revisit)ELLDEncapsulation (revisit)HLDCh 01 — Monolith (revisit)
Week 2Linked Lists (medium) & Two Pointers → SOLID & Observer → Caching
Day 8DSA

DSA — Linked Lists: medium problems

DSALinked List CycleEDSAPalindrome Linked ListEDSAAdd Two NumbersMDSARemove Nth Node from EndM
Day 9DSA

DSA — Two Pointers: easy → medium

Two Pointers — Pattern GuideDSAMove ZeroesEDSAValid PalindromeEDSATwo Sum IIMDSAContainer With Most WaterM
Day 10LLD

LLD — SOLID Principles

LLDDesign PrinciplesLLDSOLID
Day 11LLD

LLD — Strategy & Observer Patterns

LLDStrategy PatternLLDObserver PatternLLDCommand Pattern
Day 12HLD

HLD — Caching with Redis

HLDCh 03 — Caching with Redis
Day 13HLD

HLD — Load Balancer & Stateless

HLDCh 06 — Load BalancerHLDCh 07 — Stateless Services
Day 14Revision

Revision — Week 2

DSA3SumHDSAReorder ListMLLDStrategy (revisit)HLDCh 03 — Caching (revisit)
Week 3Sliding Window & Stack → Creational Patterns → DB Replicas
Day 15DSA

DSA — Sliding Window: fixed & variable

Sliding Window — Pattern GuideDSAMax Sum Subarray KEDSAPermutation in StringMDSALongest Substring Without RepeatingMDSAMin Size Subarray SumM
Day 16DSA

DSA — Sliding Window hard + Stack easy/medium

DSAMinimum Window SubstringHStacks & Queues — Pattern GuideDSAValid ParenthesesEDSAEvaluate Reverse Polish NotationMDSADecode StringM
Day 17LLD

LLD — Factory & Builder Patterns

LLDFactory PatternLLDAbstract FactoryLLDBuilder Pattern
Day 18LLD

LLD — Vending Machine (full design walkthrough)

LLDVending MachineLLDState Pattern
Day 19HLD

HLD — Read Replicas

HLDCh 04 — Read Replicas
Day 20HLD

HLD — Indexes & Query Performance

HLDCh 05 — Indexes & Query Perf.
Day 21Revision

Revision — Week 3

DSAMax Consecutive Ones IIIMDSAMinimum Window Substring (revisit)HLLDVending Machine (revisit)HLDCh 04 — Replicas (revisit)
Week 5Binary Trees & BFS → Booking Systems → CDN & API Gateway
Day 29DSA

DSA — Binary Trees: easy → medium

Binary Trees — Pattern GuideDSAInvert Binary TreeEDSAMaximum Depth of Binary TreeEDSADiameter of Binary TreeEDSABalanced Binary TreeEDSABinary Tree PathsE
Day 30DSA

DSA — BFS: trees & grids

BFS — Pattern GuideDSALevel Order TraversalEDSABinary Tree Side ViewMDSARotting OrangesMDSA01 MatrixM
Day 31LLD

LLD — BookMyShow & Library Management

LLDBookMyShow Booking SystemLLDLibrary Management
Day 32LLD

LLD — Proxy, Adapter & Decorator Patterns

LLDDecorator PatternLLDProxy PatternLLDAdapter Pattern
Day 33HLD

HLD — CDN

HLDCh 10 — CDN
Day 34HLD

HLD — API Gateway

HLDCh 11 — API Gateway
Day 35Revision

Revision — Week 5

DSAWord LadderHDSALCAMLLDBookMyShow (revisit)HLDCh 10 — CDN (revisit)
Week 6DFS & Graph Fundamentals → Board Games → HLD Reliability
Day 36DSA

DSA — DFS: tree paths & backtracking

DFS — Pattern GuideDSAPath SumEDSALowest Common AncestorMDSANumber of IslandsMDSASubsetsM
Day 37DSA

DSA — Graphs: traversal, cycle detection & topo sort

Graphs — Pattern GuideDSAGraph TraversalEDSAUndirected Cycle DetectionMDSACourse Schedule (Topo Sort)MDSATopological SortM
Day 38LLD

LLD — Board Games: TicTacToe & Chess

LLDTic Tac ToeLLDChess Design
Day 39LLD

LLD — Snake & Ladder + Meeting Scheduler

LLDSnake & LadderLLDMeeting SchedulerLLDMediator Pattern
Day 40HLD

HLD — Real-Time Communication

HLDCh 12 — Real-Time Communication
Day 41HLD

HLD — Observability, Failure & Recovery

HLDCh 13 — Observability, Failure & Recovery
Day 42Revision

Revision — Week 6 (Mid-point!)

DSACourse Schedule (revisit)MDSANumber of Islands (revisit)MLLDChess (revisit)HLDCh 13 — Reliability (revisit)
Week 7Union Find & Greedy → Finance LLD → HLD Interview Framework
Day 43DSA

DSA — Union Find: components & connectivity

Union Find — Pattern GuideDSANumber of ProvincesMDSARedundant ConnectionMDSAPacific Atlantic Water FlowM
Day 44DSA

DSA — Greedy: intervals & scheduling

DSAMerge IntervalsMDSANon-overlapping IntervalsMDSAJump GameMDSAGas StationM
Day 45LLD

LLD — Splitwise & Digital Wallet

LLDSplitwiseLLDDigital Wallet
Day 46LLD

LLD — Payment Gateway & Hotel Booking

LLDPayment GatewayLLDHotel Booking
Day 47HLD

HLD — The Interview Framework

HLDCh 14 — The Interview Framework
Day 48HLD

HLD — Problem Archetypes

HLDCh 15 — The Problem Archetypes
Day 49Revision

Revision — Week 7

DSAMerge Intervals (revisit)MDSAJump Game (revisit)MLLDSplitwise (revisit)HLDCh 14 — Framework (revisit)
Week 8DP Foundations [3 DSA days] → Cache & Rate Limiter → HLD Twitter
Day 50DSA

DSA — DP: linear 1D

Dynamic Programming — Pattern GuideDSAClimbing StairsEDSAMin Cost Climbing StairsEDSAHouse RobberM
Day 51DSA

DSA — DP: knapsack & unbounded

DSAPartition Equal Subset SumMDSA0/1 KnapsackMDSACoin ChangeM
Day 52DSA

DSA — DP: sequences [extra DSA day]

DSALongest Common SubsequenceMDSAEdit DistanceHDSALongest Increasing SubsequenceM
Day 53LLD

LLD — LRU Cache & Key-Value Store

LLDLRU Cache DesignLLDKey-Value Store
Day 54HLD

HLD — Design Twitter / Feed

HLDCh 16 — Design Twitter / Feed
Day 55LLD

LLD — Rate Limiter & Autocomplete

LLDRate LimiterLLDAutocomplete
Day 56Revision

Revision — Week 8

DSACoin Change (revisit)MDSAEdit Distance (revisit)HLLDLRU Cache (revisit)HLDCh 16 — Twitter (revisit)
Week 9DP Grid & Sorting → Marketplace LLD → HLD Chat & Video
Day 57DSA

DSA — DP: grid problems

DSAUnique PathsMDSAUnique Paths IIMDSATriangleMDSAMin Falling Path SumM
Day 58DSA

DSA — Sorting algorithms

Sorting — Pattern GuideDSAMerge SortMDSAQuick SortMDSACyclic SortMDSAReverse PairsH
Day 59LLD

LLD — Cab Booking (Uber/Ola)

LLDCab BookingLLDTemplate Method Pattern
Day 60LLD

LLD — Food Delivery & Marketplace

LLDFood DeliveryLLDBridge PatternLLDFlyweight Pattern
Day 61HLD

HLD — WhatsApp / Chat

HLDCh 19 — WhatsApp / Chat
Day 62HLD

HLD — YouTube / Netflix

HLDCh 20 — YouTube / Netflix
Day 63Revision

Revision — Week 9

DSAUnique Paths (revisit)MDSACyclic Sort (revisit)MLLDCab Booking (revisit)HLDCh 19 — Chat (revisit)
Week 10Backtracking & Advanced DSA → Remaining LLD → HLD URL & KV Store
Day 64DSA

DSA — Backtracking

Backtracking — Pattern GuideDSASubsetsMDSABest Time to Buy & Sell StockEDSADungeon GameH
Day 65DSA

DSA — Hard mixed (Trapping Rain + Largest Histogram)

DSATrapping Rain WaterHDSASliding Window MaximumHDSAMatrix Chain MultiplicationH
Day 66LLD

LLD — Iterator, Chain of Responsibility & Visitor

LLDIterator PatternLLDChain of ResponsibilityLLDVisitor Pattern
Day 67LLD

LLD — Memento & Interpreter Patterns

LLDMemento PatternLLDInterpreter Pattern
Day 68HLD

HLD — URL Shortener

HLDCh 23 — URL Shortener
Day 69HLD

HLD — Key-Value Store

HLDCh 24 — Key-Value Store
Day 70Revision

Revision — Week 10

DSATrapping Rain Water (revisit)HDSASliding Window Maximum (revisit)HLLDIterator (revisit)HLDCh 24 — KV Store (revisit)
Week 11Heaps & Shortest Path → Advanced LLD Revision → HLD Systems
Day 71DSA

DSA — Heaps & Priority Queues

Heaps — Pattern GuideDSAMerge K Sorted ListsHDSAOpen LockMDSAPerfect SquaresM
Day 72DSA

DSA — Shortest Path algorithms

Shortest Path — Pattern GuideDSAWord LadderHDSATraveling Salesperson (Bitmask DP)H
Day 73LLD

LLD Revision — State Machines round-up

LLDVending Machine (final)LLDATM (final)LLDElevator System (final)
Day 74LLD

LLD Revision — Booking & Finance round-up

LLDParking Lot (final)LLDSplitwise (final)LLDCab Booking (final)
Day 75HLD

HLD — Ticket Booking (Ticketmaster)

HLDCh 18 — Ticket Booking
Day 76HLD

HLD — Uber & Search Autocomplete

HLDCh 21 — Uber / ProximityHLDCh 22 — Search Autocomplete
Day 77Revision

Revision — Week 11

DSAWord Ladder (revisit)HDSAMerge K Sorted Lists (revisit)HLLDBookMyShow (final revisit)HLDCh 18 — Ticketmaster (revisit)
Week 12🏁 Grand Revision Week — Everything
Day 78Revision

Revision DSA — Arrays, Pointers, Window

DSAMin Window SubstringHDSATrapping Rain WaterHDSA3SumH
Day 79Revision

Revision DSA — Trees, BFS, Graphs

DSAWord LadderHDSACourse ScheduleMDSALCAM
Day 80Revision

Revision DSA — DP & Backtracking

DSAEdit DistanceHDSALCSMDSADungeon GameH
Day 81Revision

Revision LLD — State Machines & Patterns

LLDVending MachineLLDParking LotLLDStrategy Pattern
Day 82Revision

Revision HLD — Foundations & Scale

HLDCh 03 — CachingHLDCh 06 — Load BalancerHLDCh 09 — Sharding
Day 83Revision

Revision HLD — Systems

HLDCh 14 — Interview FrameworkHLDCh 16 — Design TwitterHLDCh 19 — Chat
Day 84Revision

🎯 Final Mock Prep

DSASliding Window MaximumHLLDElevator SystemHLDCh 24 — Key-Value StoreHLDCh 20 — YouTube / Netflix