Learn
Understand first, then drill
C++ rules and DSA patterns, then the matching problems. The classroom is the step-by-step walkthrough.
Open classroomTrack A
C++ Fundamentals
Lesson 01 · 12 min
C++ Setup, Hello & I/O
How a C++ program runs, iostream, cin/cout, competitive programming fast I/O.
Lesson 02 · 15 min
Types, Variables & Operators
int vs long long, bool, char, overflow traps, and operator basics.
Lesson 03 · 14 min
if / for / while — Control Flow
Loops, early returns, and the patterns you reuse in every DSA solution.
Lesson 04 · 16 min
Functions, Classes & Pass-by-Reference
How LeetCode Solution classes work, and why we pass vectors by reference.
Lesson 05 · 18 min
vector — Your Default Array
size, push_back, indexing, sort, and the mistakes that cause TLE/WA.
Lesson 06 · 15 min
string Basics for Interviews
Indexing chars, ascii tricks, two pointers on strings, and anagram counting.
Track B
DSA Patterns
Ordered from your LeetCode baseline. Each topic opens a full lesson before the problem list.
01Arrays
Study lessonTreat every array problem as: What do I know at index i? What must I remember from the past?
02Hashing
Study lessonReplace nested loops with unordered_map / unordered_set lookups.
03Two Pointers
Study lessonMove left/right based on a condition instead of checking all pairs.
04Sliding Window
Study lessonMaintain [L,R] that satisfies a constraint; answer from length/sum/counts.
05Binary Search
Study lessonOn a sorted range, throw away half each step.
06Stack & Monotonic Stack
Study lessonLIFO for matching, undo, and next-greater patterns.
07Linked List
Study lessonRedraw next pointers carefully; draw on paper first.
08Binary Trees
Study lessonAnswer for a node from left + right children.
09Intro Dynamic Programming
Study lessonReuse smaller answers via a table or rolling variables.
10HackerRank Warmup
Study lessonClassic warmup problems, taught slowly in Hindi, English, or Hinglish, then typed by you.