19 data-structure & algorithm topics taught with animated visualizations and an in-browser code sandbox. Practice AI-generated problems verified by tests, then sit a timed 3-problem mock interview.
One journey from “what is a heap?” to passing a timed coding interview — with no gap in between.
Every topic starts with a plain-English idea and an animated visualization — watch arrays split, trees rotate, and graphs get traversed step by step. Then read the code and run it yourself, right in the browser.
Generate new practice problems on demand — every one is executed against its own test cases before you see it. Work the full interview loop: trace, plan the approach, code, debug, optimize, and analyze complexity.
When you are ready, sit a real screening round: 3 problems, a 45-minute timer, your choice of difficulty, and no hints until it ends. Review your results and know exactly where you stand.
An ordered path from fundamentals to dynamic programming — every topic animated, explained in plain English, and backed by practice problems.
Binary Search
O(log n) lookup
Practice problems
Sorting
merge, quick, heap
Practice problems
Recursion
base case, call stack
Practice problems
Two Pointers
sliding window
Practice problems
Sliding Window
fixed & variable windows
Practice problems
Backtracking
choose, explore, undo
Practice problems
Bit Manipulation
AND, OR, XOR, shifts
Practice problems
Intervals
merge, overlap, greedy
Practice problems
Monotonic Stack
next greater/smaller element
Practice problems
Hash Tables
O(1) lookup
Practice problems
Heaps & PQ
min/max heap, priority Q
Practice problems
Binary Trees
BST, traversal
Practice problems
Trie
prefix tree, autocomplete
Practice problems
Graphs
BFS, DFS, shortest path
Practice problems
Dynamic Prog.
memoization, tabulation
Practice problems
Union-Find
disjoint sets, connectivity
Practice problems
Reading about algorithms doesn't make them stick. Watching them move, coding them yourself, and being tested under time pressure does.
Step-through animations for arrays, trees, graphs, heaps, stacks, queues, and every classic sorting algorithm — see exactly what the data structure is doing.
Write and run real solutions against test cases without installing anything. Instant feedback, no setup, no local environment.
Every AI-generated problem is executed against its own test cases in a sandbox before it ships to you — no broken statements, no wrong answers.
XP, levels, streaks, and review-due reminders bring you back to topics right before you would forget them.
Concept → See it → Code → Your turn → Check. A consistent five-step loop for every topic, so nothing is ever dumped on you at once.
An optional eight-step drill per problem — trace, approach, code, debug, optimize, complexity, real-world use — exactly how strong candidates think out loud.
Knowing an algorithm and producing it with a clock running are different skills. A mock interview simulates the real screening round: no hints until it ends, switch between problems freely, and submit to lock in your answers.
2 credits per session · free credits on signup
Everything you need to know before you start.
Yes — you can explore every topic, watch the animated visualizations, and run code in the browser without signing up. A free account unlocks progress tracking, and AI-generated practice problems and mock interviews use credits from the free plan.
No. Everything runs in your browser: the animated visualizations, the code editor, and the sandbox that executes your solution against test cases. There is nothing to download or configure.
Algo Coach covers 19 topics across fundamentals (arrays, strings, linked lists, stacks & queues), core algorithms (binary search, sorting, recursion, two pointers, sliding window, backtracking, bit manipulation, intervals, monotonic stack), and advanced material (hash tables, heaps, binary trees, tries, graphs, dynamic programming).
Every AI-generated problem is executed against its own test cases in a real sandbox before it ever reaches you. Problems that fail verification are repaired or discarded, so you never waste time on a broken problem statement or wrong expected outputs.
A mock interview session gives you 3 coding problems and a 45-minute timer, just like a real screening round. You pick the difficulty (Easy, Medium, Hard, or Mixed), switch freely between problems, and get no hints until the session ends — then you review your results.
LeetCode is a problem bank; Algo Coach teaches first. Each topic starts with a plain-English concept, an animated visualization you can step through, and runnable reference code — then you implement it yourself and check understanding with a quiz. Practice problems and mock interviews come after you have actually learned the idea.
Yes. The learning path is ordered from fundamentals to advanced topics, every concept is explained in plain English before any code appears, and the visualizations show what the data structure is doing at each step. The interview-prep track is optional.
Start with arrays today — watch the animation, run the code, and keep the streak going. No installs, no signup to explore.
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