Learn

These aren't reference docs. Each topic starts with something you can poke at — an interactive demo that builds the intuition before any code appears. Pick one and give it five minutes.

Core Algorithms

Two Pointers

Walk both ends toward the middle and see what falls out.

Sliding Window

The pattern that makes subarray problems click — fixed-size or shrinkable.

Hash Maps & Sets

Trade space for speed. O(1) lookup changes what's possible.

Stacks & Queues

Last in first out, first in first out. Most problems reduce to picking the right one.

Binary Search

Halve the search space every step — not just for sorted arrays.

Trees & Graphs

Nodes and edges. Most tree and graph problems boil down to traversal order.

Recursion & Backtracking

Solve it by solving a smaller version. Undo what doesn't work.

Dynamic Programming

Overlapping subproblems, optimal substructure — the real intuition behind DP.

Frontend Patterns

Debounce & Throttle

Wait until they stop, or fire at most once per interval. Two sentences, two patterns.

Memoization

Same input, same output? Cache it. useMemo and useCallback are just the React version.

Event Delegation

One handler on the parent, not fifty on the children. Events bubble — use it.

Async Patterns

The event loop, microtasks, and why your setTimeout fires after your Promise.

From Scratch

Implement the thing without using the thing. The interview question that tests understanding.

AI Agent Patterns

SSE, streaming, state machines, and the UI components that make agent features work.