Study

Every interview topic, explained subtopic by subtopic: what it is, how it works, where it is used, the questions you will get, and a quick quiz.

Arrays & Hashing

Store, look up and count data in O(1): the base of most coding interviews.

6 subtopics57 min

0/6

Two Pointers

Walk an array from two positions to turn O(n^2) scans into O(n).

5 subtopics47 min

0/5

Sliding Window

Process every contiguous range of an array or string in one pass.

5 subtopics50 min

0/5

Stack

Last in, first out: brackets, parsing, undo and the next-greater family.

5 subtopics49 min

0/5

Binary Search

Halve the search space each step, on arrays and on answers.

5 subtopics46 min

0/5

Linked Lists

Pointer manipulation: reverse, merge, detect cycles, design caches.

6 subtopics55 min

0/6

Trees & Graphs

Traversals, recursion on trees, BFS/DFS, shortest paths and connectivity.

9 subtopics90 min

0/9

Tries

Prefix trees for autocomplete, word search and XOR problems.

4 subtopics42 min

0/4

Heap / Priority Queue

Always know the smallest or largest item: top-k, merging, scheduling, medians.

5 subtopics49 min

0/5

Backtracking

Build candidates step by step and undo choices: subsets, permutations, puzzles.

6 subtopics60 min

0/6

Intervals

Sort by start or end, then sweep: merging, inserting, meeting rooms.

5 subtopics44 min

0/5

Greedy

Make the locally best choice, and know how to prove it is safe.

5 subtopics47 min

0/5

Dynamic Programming

Break problems into overlapping subproblems and reuse the answers.

6 subtopics66 min

0/6

Bit Manipulation

Work directly with binary: XOR tricks, masks and subsets.

5 subtopics48 min

0/5

Behavioural

Tell clear, honest stories about how you work with people and problems.

6 subtopics47 min

0/6

SQL

Query, join, aggregate and tune relational data.

7 subtopics72 min

0/7

OS Concepts

Processes, threads, scheduling, synchronisation and memory.

6 subtopics63 min

0/6

Networking

How data moves across the internet, from packets to HTTPS and real-time apps.

9 subtopics84 min

0/9

Recursion

Solve a problem with smaller copies of itself: the base of trees, DP and backtracking.

5 subtopics51 min

0/5