Hi👋SpeedAlgo • Deliberate Practice & Cognitive Ergonomics for Software Engineers

An interactive algorithm mastery and technical interview preparation platform published by Hiđź‘‹WebEnterprise. Built for senior and staff software engineers preparing for rigorous coding screens at top tech companies (FAANG/MAMAA).

12 Core Algorithmic Patterns & 195 Practice Problems

  • 1. Two Pointers (11 Paradigms, 35 Problems): Opposite ends, sorted pair sums, palindrome verification, trapping rain water, 3Sum, container with most water — includes the Sliding Window and Fast & Slow Pointers paradigms (contiguous subarray invariants, longest substrings, Floyd's cycle detection, linked list middle).
  • 2. Binary Search (9 Paradigms, 14 Problems): Monotonic predicate partitioning (`feasible(x)`), boundary search, rotated sorted arrays, square roots, minimum ship capacity, median of two sorted arrays, matrix median on value range.
  • 3. Bit Manipulation (5 Paradigms, 8 Problems): Counting set bits, XOR cancellation, bit reversal, bitmask pairing, maximum XOR with a bitwise trie.
  • 4. Math & Geometry (8 Paradigms, 14 Problems): Sieve of Eratosthenes, integer/roman conversions, modular arithmetic, geometric simulation.
  • 5. Tree/Graph Depth-First Search (10 Paradigms, 19 Problems): Path sums, lowest common ancestor, tree diameter, validating BSTs, tree DP (House Robber III, Binary Tree Cameras).
  • 6. Tree/Graph Breadth-First Search (4 Paradigms, 11 Problems): Level-order traversals, shortest path in unweighted graphs, zig-zag traversals, rotting oranges, word ladders.
  • 7. Graphs (10 Paradigms, 18 Problems): Topological sort, cycle detection, Dijkstra's algorithm, bipartite graph validation, network delay.
  • 8. Backtracking (6 Paradigms, 14 Problems): Subsets, permutations, combinations, constraint satisfaction, pruning, N-Queens, Sudoku solver.
  • 9. Dynamic Programming (11 Paradigms, 18 Problems): Memoization vs tabulation, 0/1 knapsack, unbounded knapsack, coin change, edit distance, longest common subsequence.
  • 10. Heap / Priority Queue (9 Paradigms, 11 Problems): Running medians, top-k elements, interval scheduling, IPO, k-way merges.
  • 11. Advanced Data Structures (6 Paradigms, 15 Problems): Trie (prefix tree), Union-Find (Disjoint Set Union), LRU Cache, LFU Cache, range-sum queries with updates.
  • 12. Intervals & Stack / Miscellaneous (11 Paradigms, 18 Problems): Merge intervals, daily temperatures, largest rectangle in histogram, trapping rain water via stack.

4-Stage Deliberate Practice Framework

  1. Stage 1 (Compare & Learn): Read the pattern's mental model, loop invariant and Big-O proof, compare the pattern's template with the problem's solution side by side, and use the step-by-step debugger. The solution can also be shown in C#, Java, TypeScript, C++, Go or Rust for almost every problem.
  2. Stage 2 (Active Recall): Rebuild the solution from memory in a code editor, with an invariant checklist and optional progressive hints, and check it against a judged test suite.
  3. Stage 3 (AI Interview Coach, coming soon): A mock-interview stage still in development; for now, students go straight from Stage 2 to Stage 4.
  4. Stage 4 (Solve on Your Own): Solve a new problem on your own against a 15-minute timer; your code is graded against a test suite. Python and TypeScript run in your browser and C# runs on our server (design problems grade in Python and TypeScript).

Equipped with a spaced-repetition review hub on a fixed 7-step schedule (1 day up to 90 days), a two-pane Studio workspace, and study notes.

Pricing, Access & Commercial Terms

  • Core Curriculum: 100% Free. No credit card required.
  • Coins: New accounts get 40 free coins once, the daily claim adds +20 coins once a day, and inviting a friend earns you +25 coins when they complete their first practice step. These are the only ways to earn coins.
  • AI Coach: Each AI coach question costs 1-5 coins, priced by the server according to its size.
  • BYOK (Bring Your Own Key): AI coaching is free with your own Google Gemini, OpenAI or OpenRouter API key (BYOK).
  • Extras: Coins also unlock extras for 24 hours: a Recall hint level (1 coin), a Solve solution reveal (2), a LeetCode problem card's solutions (1) and a pattern's extra canonical problems (1).
  • Payments & Refunds: Nothing on the site is sold for money: coins can only be earned, never bought. There are no subscriptions or charges, so there is nothing to refund.
  • Platform Operator: Hiđź‘‹WebEnterprise. Support & policies at hispeedalgo.com.