Consistent Hashing, eviction policies (LRU/LFU), and defeating the cache stampede and thundering herd problems.

Fan-out on write vs fan-out on read architectures. Optimizing for celebrity users with millions of followers.

Real-time messaging with WebSockets, presence servers, and message queues for offline delivery guaranteed.

Breaking down the state transitions for the classic 0/1 Knapsack DP problem with bottom-up tabulation.

Building an O(1) LRU Cache using Hash Map + Doubly Linked List — a top system design/coding interview question.

Traversing a binary tree level-by-level using a queue — fundamental for shortest-path problems.

CAP theorem analysis, DynamoDB architecture, Vector Clocks for conflict resolution, and Gossip protocol internals.

In-place reversal of a singly linked list — mastering this requires truly understanding pointers.

A guide to std::thread, preventing data races with std::mutex, and task-level parallelism with std::async.

std::variant and std::optional

Why C++17's algebraic data types replace output-parameter hacks and null pointer returns for safer APIs.