Master programming from zero to placement-ready. Code in 3 languages, solve real company problems, crack TCS NQT, Infosys InfyTQ and more.

Python

Most popular for placements. TCS, Infosys, Wipro all accept Python — start here if you are new to coding.

TopicLevel

Introduction to Python & SetupBeginner

TCSInfosysWipro

Variables & Data TypesBeginner

TCSInfosysWipro

Input & OutputBeginner

TCSInfosysWipro

Operators (Arithmetic, Comparison, Logical, Bitwise)Beginner

TCSInfosysWipro

Type Casting & ConversionBeginner

TCSInfosysWipro

Conditional StatementsBeginner

TCSInfosysWipro

for LoopBeginner

TCSInfosysWipro

while LoopBeginner

TCSInfosysWipro

break, continue, passBeginner

TCSInfosysWipro

Nested Loops & Pattern ProgramsBeginner

TCSInfosysWipro

Strings — Basics & SlicingBeginner

TCSInfosysWipro

String Methods & OperationsBeginner

TCSInfosysWipro

Lists — Creation, Slicing, MethodsBeginner

TCSInfosysWipro

Tuples & SetsBeginner

TCSInfosysWipro

DictionariesBeginner

TCSInfosysWipro

TopicLevel

Functions — Definition, Arguments, ReturnIntermediate

TCSInfosysWipro

Default, *args, **kwargsIntermediate

TCSInfosysWipro

Lambda, map(), filter(), reduce()Intermediate

TCSInfosysWipro

List ComprehensionsIntermediate

TCSInfosysWipro

File Handling (read, write, append)Intermediate

TCSInfosysWipro

Exception Handling (try-except-finally)Intermediate

TCSInfosysWipro

Modules & Packages (import, pip)Intermediate

TCSInfosysWipro

OOP — Classes & ObjectsIntermediate

TCSInfosysWipro

OOP — Inheritance & PolymorphismIntermediate

TCSInfosysWipro

OOP — Encapsulation & AbstractionIntermediate

TCSInfosysWipro

Iterators & GeneratorsIntermediate

TCSInfosysWipro

DecoratorsIntermediate

TCSInfosysWipro

Regular ExpressionsIntermediate

TCSInfosysWipro

Working with JSONIntermediate

TCSInfosysWipro

Virtual Environments & pipIntermediate

TCSAmazonInfosys

TopicLevel

Collections Module — Counter, defaultdict, deque, namedtupleAdvanced

TCSInfosysAmazon

Multithreading & Multiprocessing — Concurrency in PythonAdvanced

AmazonGoogleTCS

Database Connectivity (sqlite3)Advanced

TCSAmazonInfosys

API Calls — Working with REST APIs using requestsAdvanced

TCSInfosysAmazon

NumPy BasicsAdvanced

TCSInfosysAmazon

Pandas BasicsAdvanced

TCSInfosysAmazon

Matplotlib BasicsAdvanced

TCSInfosysAmazon

Web Scraping (BeautifulSoup)Advanced

AmazonGoogleTCS

Flask Basics — Building Web APIs with PythonAdvanced

AmazonGoogleTCS

Best Practices & PEP 8 — Writing Clean, Professional PythonAdvanced

TCSAmazonGoogle

C Programming

Foundation of systems programming. Essential for TCS NQT and Wipro NLTH.

TopicLevel

Introduction to C & CompilationBeginner

TCSInfosysWipro

Variables, Data Types & sizeofBeginner

TCSInfosysWipro

printf & scanf — Input/Output in CBeginner

TCSWiproInfosys

Operators — Arithmetic, Relational, Logical, BitwiseBeginner

TCSWiproInfosys

Type Casting & ConversionBeginner

TCSWiproInfosys

Conditional Statements — if-else & switch-caseBeginner

TCSWiproInfosys

Loops — for, while, do-whileBeginner

TCSInfosysWipro

Nested Loops & Pattern ProgramsBeginner

TCSWiproCognizant

Arrays — 1DBeginner

TCSInfosysWipro

Arrays — 2D (Matrix)Beginner

TCSInfosysWipro

Strings — Basics & char ArraysBeginner

TCSInfosysWipro

String Functions (strlen, strcpy, strcmp)Beginner

TCSInfosysWipro

Functions — Declaration & DefinitionBeginner

TCSInfosysWipro

RecursionBeginner

TCSInfosysWipro

Storage Classes (auto, static, extern, register)Beginner

TCSInfosysWipro

TopicLevel

Pointers — BasicsIntermediate

TCSWiproInfosys

Pointer ArithmeticIntermediate

TCSWiproInfosys

Pointers & ArraysIntermediate

TCSWiproInfosys

Pointers & Functions — Call by ReferenceIntermediate

TCSWiproInfosys

Dynamic Memory Allocation — malloc, calloc, realloc, freeIntermediate

TCSWiproInfosys

Structures in CIntermediate

TCSInfosysWipro

Unions & Enums in CIntermediate

TCSInfosysWipro

Typedef in CIntermediate

TCSInfosysWipro

File Handling in CIntermediate

TCSInfosysWipro

C Preprocessor DirectivesIntermediate

TCSInfosysWipro

Command Line Arguments in CIntermediate

TCSInfosysWipro

Bitwise Operations in CIntermediate

TCSInfosysWipro

TopicLevel

Function PointersAdvanced

TCSInfosysWipro

Self-referential StructuresAdvanced

TCSInfosysWipro

Linked List Implementation in CAdvanced

TCSInfosysWipro

Stack Implementation in CAdvanced

TCSInfosysWipro

Queue Implementation in CAdvanced

TCSInfosysWipro

Binary Tree in CAdvanced

TCSInfosysWipro

Sorting Algorithms in CAdvanced

TCSInfosysWipro

Memory Management Best Practices in CAdvanced

TCSInfosysWipro

Java

Enterprise standard. Most asked in Infosys, Cognizant, Capgemini placement rounds.

TopicLevel

Introduction to Java & JVMBeginner

TCSInfosysWipro

Variables, Data Types & Type Casting in JavaBeginner

TCSInfosysWipro

Scanner Class — Input/Output in JavaBeginner

TCSInfosysWipro

Java Operators & ExpressionsBeginner

TCSInfosysWipro

Java Control Flow — if-else & switchBeginner

TCSInfosysWipro

Java Loops — for, while, do-while, for-eachBeginner

TCSInfosysWipro

Java Arrays — 1D and 2DBeginner

TCSInfosysWipro

Java StringsBeginner

TCSInfosysWipro

Java String MethodsBeginner

TCSInfosysWipro

Java MethodsBeginner

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Java Method OverloadingBeginner

TCSInfosysWipro

Java RecursionBeginner

TCSInfosysWipro

Packages & Access ModifiersBeginner

TCSInfosysWipro

Wrapper Classes, Autoboxing & the Integer CacheBeginner

TCSInfosysWipro

Math & RandomBeginner

TCSInfosysWipro

TopicLevel

Classes & ObjectsIntermediate

TCSInfosysWipro

ConstructorsIntermediate

TCSInfosysWipro

Java — InheritanceIntermediate

TCSInfosysWipro

Java — PolymorphismIntermediate

TCSInfosysWipro

Java — AbstractionIntermediate

TCSInfosysWipro

Java — EncapsulationIntermediate

TCSInfosysWipro

Java — Exception HandlingIntermediate

TCSInfosysWipro

Java Collections — ArrayList & LinkedListIntermediate

TCSInfosysWipro

Java Collections — HashMap & HashSetIntermediate

TCSInfosysAmazon

Java Collections — Stack, Queue, Deque, PriorityQueueIntermediate

TCSInfosysAmazon

Java — Comparable & ComparatorIntermediate

TCSInfosysAmazon

Java — File Handling (java.io and java.nio.file)Intermediate

TCSInfosysWipro

Java — GenericsIntermediate

TCSInfosysAmazon

Java — Lambda ExpressionsIntermediate

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Java — Streams APIIntermediate

TCSInfosysAmazon

JDBC — Database ConnectivityIntermediate

TCSInfosysWipro

Java 8+ Features SummaryIntermediate

TCSInfosysAmazon

Design Patterns BasicsIntermediate

TCSInfosysAmazon

TopicLevel

Multithreading — Thread, Runnable, ConcurrencyAdvanced

TCSInfosysWipro

Synchronization — Locks, Atomic, Producer-ConsumerAdvanced

TCSInfosysAmazon

SQL

Every company tests SQL. Master JOINs, subqueries, window functions to crack any data round.

TopicLevel

Introduction to Databases & SQLBeginner

TCSInfosysWipro

sql-ddl-create-alter-dropBeginner

TCSInfosysWipro

INSERT, UPDATE, DELETE — Data Manipulation Language (DML)Beginner

TCSInfosysWipro

SELECT & WHERE Clause — Querying and Filtering DataBeginner

TCSInfosysWipro

ORDER BY, LIMIT & DISTINCT — Sorting, Pagination, and DeduplicationBeginner

TCSInfosysWipro

SQL Aggregate Functions — COUNT, SUM, AVG, MIN, MAXBeginner

TCSInfosysWipro

TopicLevel

SQL GROUP BY & HAVING — Aggregating by GroupsIntermediate

TCSInfosysWipro

SQL JOINs — INNER, LEFT, RIGHT, FULL OUTERIntermediate

TCSInfosysWipro

SQL Self-Join & Cross-Join — Joining Tables with ThemselvesIntermediate

TCSInfosysWipro

SQL Subqueries — Queries Inside QueriesIntermediate

TCSInfosysWipro

SQL EXISTS, IN, ANY, ALL — Membership and Comparison OperatorsIntermediate

TCSInfosysWipro

SQL Set Operations — UNION, INTERSECT, EXCEPTIntermediate

TCSInfosysWipro

SQL Views — Virtual Tables for Simplicity and SecurityIntermediate

TCSInfosysWipro

SQL — TransactionsIntermediate

TCSInfosysWipro

SQL — Normalization (1NF, 2NF, 3NF, BCNF)Intermediate

TCSInfosysWipro

TopicLevel

SQL Indexes & PerformanceAdvanced

TCSInfosysWipro

SQL — Stored ProceduresAdvanced

TCSInfosysWipro

SQL — TriggersAdvanced

TCSInfosysWipro

SQL — Window FunctionsAdvanced

AmazonGoogleMicrosoft

SQL — Interview Top Patterns (Capstone)Advanced

AmazonGoogleMicrosoft

Data Structures

Core of every coding interview. Arrays, Trees, Graphs, Hashing — non-negotiable for product companies.

TopicLevel

DSA Introduction: What, Why, and HowBeginner

TCSInfosysWipro

Time Complexity: Big-O and the Growth of AlgorithmsBeginner

TCSInfosysWipro

Space Complexity: Auxiliary Memory and Trade-offsBeginner

TCSInfosysAmazon

Recursion BasicsBeginner

TCSInfosysWipro

Arrays - IntroductionBeginner

TCSInfosysWipro

Arrays - Traversal PatternsBeginner

TCSInfosysWipro

Linked Lists — IntroductionBeginner

AmazonGoogleMicrosoft

TopicLevel

Backtracking IntroductionIntermediate

AmazonGoogleMicrosoft

Arrays - Searching (Linear and Binary)Intermediate

TCSInfosysWipro

Arrays - Two-Pointer TechniqueIntermediate

AmazonGoogleMicrosoft

Arrays - Sliding WindowIntermediate

TCSInfosysWipro

Arrays - Prefix SumIntermediate

TCSInfosysWipro

Arrays - Sorting BasicsIntermediate

TCSInfosysWipro

Arrays - Advanced Sorting (Merge, Quick, Heap)Intermediate

AmazonGoogleMicrosoft

Arrays - Kadane's Algorithm (Maximum Subarray)Intermediate

AmazonGoogleMicrosoft

Arrays - Interview Top-20 (Capstone Synthesis)Intermediate

AmazonGoogleMicrosoft

Strings - Introduction (Immutability, Operations, Methods)Intermediate

AmazonGoogleMicrosoft

Strings - String Matching Basics (Naive and Beyond)Intermediate

AmazonGoogleMicrosoft

Strings - String Manipulation (Reverse, Transform, Build)Intermediate

AmazonGoogleMicrosoft

KMP — String Pattern MatchingIntermediate

AmazonGoogleMicrosoft

Rabin-Karp String MatchingIntermediate

AmazonGoogleMicrosoft

Regular Expressions (Regex)Intermediate

AmazonGoogleMicrosoft

Palindromes and AnagramsIntermediate

AmazonGoogleMicrosoft

Singly Linked Lists — Operations and PatternsIntermediate

AmazonGoogleMicrosoft

Doubly and Circular Linked ListsIntermediate

AmazonGoogleMicrosoft

Linked List Cycle Detection - Floyd's AlgorithmIntermediate

AmazonGoogleMicrosoft

Linked List Sorting and Arithmetic - Merge Sort, Dutch Flag, and LC 2/445Intermediate

AmazonGoogleMicrosoft

Stacks Introduction - LIFO, Implementations, and Classic ProblemsIntermediate

AmazonGoogleMicrosoft

Monotonic Stacks - Next Greater Element and Span ProblemsIntermediate

AmazonGoogleMicrosoft

Queues - IntroductionIntermediate

AmazonMicrosoftGoogle

Deque and Circular Queues (Sliding Window Maximum)Intermediate

AmazonGoogleMeta

Trees Introduction (TreeNode, Tree Types, Representations, Recursion)Intermediate

AmazonGoogleMeta

Tree Traversals (Preorder, Inorder, Postorder, BFS, Morris)Intermediate

AmazonGoogleMeta

Trie (Prefix Tree): O(L) String Lookups and Prefix QueriesIntermediate

GoogleAmazonMeta

Graph IntroductionIntermediate

AmazonGoogleMeta

Graph RepresentationsIntermediate

AmazonGoogleMeta

Breadth-First Search (BFS)Intermediate

AmazonGoogleMeta

Depth-First Search (DFS)Intermediate

AmazonGoogleMeta

Connected ComponentsIntermediate

AmazonGoogleMeta

Topological Sort — Kahn's Algorithm & DFS PostorderIntermediate

AmazonGoogleMeta

Dijkstra's Algorithm — Shortest Paths on Non-Negative Weighted GraphsIntermediate

AmazonGoogleMeta

Bellman-Ford Algorithm — Shortest Paths with Negative Edges & Cycle DetectionIntermediate

AmazonGoogleMeta

Minimum Spanning Tree — Kruskal's & Prim'sIntermediate

AmazonGoogleMeta

Eulerian Path & Circuit — Hierholzer, Fleury, de BruijnIntermediate

GoogleMetaAmazon

TopicLevel

Linked List Advanced Interview Problems - Clone, Reorder, ReservoirAdvanced

AmazonGoogleMicrosoft

Advanced Stack Applications - Histogram, Rain Water, RPNAdvanced

AmazonGoogleMicrosoft

Priority Queue and Binary Heap (heapq, Top-K, Median from Stream)Advanced

AmazonGoogleMeta

Binary Search Trees (Invariant, Operations, Validation, LCA, Kth Smallest)Advanced

AmazonGoogleMeta

AVL Trees — The First Self-Balancing BSTAdvanced

GoogleAmazonMicrosoft

Red-Black Trees: Production-Grade Self-Balancing BSTsAdvanced

GoogleAmazonMicrosoft

Segment Trees: Range Queries with Updates in O(log n)Advanced

GoogleAmazonMeta

Fenwick Tree (BIT): O(log n) Prefix Sums and Point UpdatesAdvanced

GoogleAmazonMeta

Trie Applications: Bit Tries, Autocomplete, and Magic DictionaryAdvanced

GoogleAmazonMeta

Articulation Points & Bridges — Tarjan's Low-LinkAdvanced

AmazonGoogleMeta

Strongly Connected Components — Kosaraju & TarjanAdvanced

AmazonGoogleMeta

Network Flow — Max-Flow, Min-Cut, Ford-Fulkerson, Edmonds-KarpAdvanced

GoogleAmazonMeta

Bipartite Matching — Kuhn's, Hopcroft-Karp, KoenigAdvanced

GoogleMetaAmazon

Hamiltonian Path & Circuit — Bitmask DP, Backtracking, Dirac's TheoremAdvanced

GoogleMetaAmazon

Travelling Salesman — Held-Karp, Branch-and-Bound, MST 2-ApproxAdvanced

GoogleMetaAmazon

2-SAT — SCC-Based Linear Boolean SatisfiabilityAdvanced

MetaGoogleAmazon

Dynamic Programming — Introduction & MemoizationAdvanced

FirstGrade Practice

1-D Dynamic Programming — TabulationAdvanced

FirstGrade Practice

Grid DP — 2-D TablesAdvanced

FirstGrade Practice

0/1 Knapsack — The Take-or-Skip TableAdvanced

FirstGrade Practice

String DP — LCS & Edit DistanceAdvanced

FirstGrade Practice

Longest Increasing SubsequenceAdvanced

FirstGrade Practice

Algorithms

Sorting, DP, greedy, backtracking — crack any coding round at Amazon, Google, Zoho.

TopicLevel

Algorithms — Asymptotic Analysis (Big-O, Theta, Omega)Beginner

TCSInfosysWipro

TopicLevel

Algorithms — Divide and Conquer (The Paradigm)Intermediate

TCSInfosysWipro

Algorithms — Recurrences & the Master TheoremIntermediate

GATE CSGATE DAAmazon

Greedy Algorithms — Proving the Obvious ChoiceIntermediate

TCSInfosysWipro

TopicLevel

Backtracking — Pruning the State-Space TreeAdvanced

TCSInfosysWipro

Git & Version Control

Master Git for every placement. TCS NQT, Infosys, Wipro all test Git basics in HR rounds.

TopicLevel

Git — Introduction to Version ControlBeginner

TCS NQTInfosys InfyTQWipro Elite NLTH

Git — Installation & First-Time ConfigBeginner

TCS NQTInfosys InfyTQWipro Elite NLTH

Git — Your First Repository (init, add, commit)Beginner

TCS NQTInfosys InfyTQWipro Elite NLTH

Git — Inspecting Your Work (status, log, diff)Beginner

TCS NQTInfosys InfyTQWipro

Git — Undoing Changes (restore, reset, revert)Beginner

TCS NQTInfosys InfyTQWipro

Git — Ignoring Files with .gitignoreBeginner

TCS NQTInfosys InfyTQWipro

TopicLevel

Git — Branching (branch, switch, checkout)Intermediate

TCS NQTInfosys InfyTQWipro

Git — Merging & Resolving ConflictsIntermediate

TCS NQTInfosys InfyTQWipro

Git — Stashing Work in ProgressIntermediate

TCS NQTInfosys InfyTQWipro

Git — Working with Remotes (clone, fetch, pull, push)Intermediate

TCS NQTInfosys InfyTQWipro

Git — Feature-Branch & Pull-Request WorkflowIntermediate

TCS NQTInfosys InfyTQWipro

TopicLevel

Git — Rebasing & Rewriting HistoryAdvanced

TCS NQTInfosys InfyTQWipro

System Design

HLD + LLD for product company interviews. Razorpay, Flipkart, Swiggy, Zerodha-level depth.

TopicLevel

What Is System Design? — HLD vs LLDBeginner

FirstGrade Practice

TopicLevel

Scalability — One Server to One Crore UsersIntermediate

FirstGrade Practice

Load Balancing — The Traffic Police of the InternetIntermediate

FirstGrade Practice

Caching — Speed at IPL ScaleIntermediate

FirstGrade Practice

CDN — Content Delivery NetworksIntermediate

FirstGrade Practice

Message Queues — Async & DecouplingIntermediate

FirstGrade Practice

Rate Limiting — Protecting Your APIIntermediate

FirstGrade Practice

API Design — REST, GraphQL & gRPCIntermediate

FirstGrade Practice

Data Partitioning & Replication — When One Database Isn't EnoughIntermediate

FirstGrade Practice

SQL vs NoSQL — Data Modeling and the Datastore DecisionIntermediate

FirstGrade Practice

Consistency, CAP & Quorums — One Truth, Three CopiesIntermediate

FirstGrade Practice

TopicLevel

SOLID Principles — Design That Survives ChangeAdvanced

FirstGrade Practice

Creational Patterns — Factory, Builder, Singleton, PrototypeAdvanced

FirstGrade Practice

Structural Patterns — Adapter, Decorator, Facade, ProxyAdvanced

FirstGrade Practice

Behavioral Patterns — Observer, Strategy, State, IteratorAdvanced

FirstGrade Practice

Design a Parking Lot — LLDAdvanced

FirstGrade Practice

Design a Library Management System — LLDAdvanced

FirstGrade Practice

Design a URL Shortener (bit.ly) — HLDAdvanced

FirstGrade Practice

Design WhatsApp (Chat at Scale) — HLDAdvanced

FirstGrade Practice

Design the Twitter Timeline — HLDAdvanced

FirstGrade Practice

Design Video Streaming (Netflix / Hotstar) — HLDAdvanced

FirstGrade Practice

Design Ride-Sharing (Uber / Ola) — HLDAdvanced

FirstGrade Practice

Design a Payment Gateway (UPI / Razorpay) — HLDAdvanced

FirstGrade Practice

AI & Machine Learning

Build every model by hand and watch it learn. GATE DA + data-science interviews + the GenAI stack — from "what is ML?" to interview-ready.

TopicLevel

What ML Is (and Isn't) — Rules vs LearningBeginner

FirstGrade Practice

Data Thinking — Features, Labels, Train/Test DisciplineBeginner

FirstGrade Practice

Descriptive Stats from Scratch — Mean, Spread, CorrelationBeginner

FirstGrade Practice

Gradients Visually — The Ball That Rolls DownhillBeginner

FirstGrade Practice

TopicLevel

Linear Regression from Scratch — The Line That LearnsIntermediate

FirstGrade Practice

TopicLevel

How LLMs Actually Work — From Tokens to the Next-Token LoopAdvanced

FirstGrade Practice

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242 Topics.Python. C. Java. DSA.

Python

C Programming

Java

SQL

Data Structures

Algorithms

Git & Version Control

System Design

AI & Machine Learning

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242 Topics.
Python. C. Java. DSA.