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Interview prep,
patterns first.

Twelve algorithmic patterns beat three thousand shuffled problems. Alpha Codepairs a pattern-indexed catalog with adaptive diagnostics, system design, behavioral scaffolds, and live mocks — at a price that doesn't require four subscriptions.

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patterns/monotonic-stack.ts
// Scenario: Next Rainy Day
// Concept: monotonic decreasing stack

function daysUntilRain(forecast: number[]) {
  const wait = new Array(forecast.length).fill(0);
  const stack: number[] = [];

  for (let i = 0; i < forecast.length; i++) {
    while (stack.length && forecast[stack.at(-1)!] < forecast[i]) {
      const j = stack.pop()!;
      wait[j] = i - j;
    }
    stack.push(i);
  }
  return wait;
}
Pattern: Monotonic Stack · O(n)diagnostic → 4 / 12
12Patterns, not farms
$19/moAll-in price
L4 → Staff+Designed for
IncludedML eng track
Patterns · not farms

Learn the twelve shapes that solve the thousand.

Every interview problem is a re-dressed pattern. We teach the shape once — then drill it across fresh scenarios you won't find on any catalog.

Sliding Window

pattern

Variable and fixed windows for contiguous-range problems.

  • Pharmacy Pickup
  • Rolling Peak Sensor
  • Unique DNA Run

Two Pointers

pattern

Converging scans that collapse O(n²) brute force to O(n).

  • Scale Balancer
  • License Plate Mirror
  • Triple Alloy

Monotonic Stack

pattern

Stack invariants for next-greater and histogram problems.

  • Next Rainy Day
  • Skyline Vault
  • Convoy Merge

Prefix & Suffix

pattern

Precompute once, query in O(1). The duct-tape of arrays.

  • Exclusive Revenue
  • Range Tally
  • Running Balance

Binary Search on Answer

pattern

When the predicate is monotonic, search the result space.

  • Bandwidth Throttle
  • Hiker's Ridge
  • Deadline Bake

Heap & Priority Queue

pattern

Top-K, scheduling, and merge-K without sorting the world.

  • Leaderboard Live-Rank
  • Barista Rotation
  • Multi-Feed Merger

Union-Find

pattern

Connectivity and cycle detection in near-constant time.

  • Friend-Circle Counter
  • Extra Cable Finder
  • LAN Mesh Audit

Topological Sort

pattern

Order anything with dependencies. Build systems live here.

  • Build-Order Planner
  • Dialect Sorter
  • Certification Track

Graph BFS / DFS

pattern

Flood fill, shortest hops, and multi-source frontiers.

  • Oil Patch Count
  • Firefront Spread
  • Exit-Sign Distances

Dynamic Programming

pattern

State machines for optimization. 1-D, 2-D, and interval forms.

  • Ski Lift Tolls
  • DNA Commonality
  • Typo Repair Cost

Backtracking

pattern

Structured search with pruning. Subsets, permutations, grids.

  • Pizza Topping Combos
  • Radar Placement
  • Maze Inscription

Interval Sweep

pattern

Sort, sweep, and merge. The shape of calendars and logs.

  • Shift Log Compaction
  • Calendar Slot Insert
  • Studio Booking
Real code · not puzzle boxes

Debug a repo. Extend a feature.
That's how interviews actually run now.

Modern loops hand you a multi-file codebase and ask you to ship. Our IDE mode drops you into a running project with failing tests, a stack trace, and a clock. Practice the skill you'll actually be graded on.

  • Multi-file scaffolds, not single-function stubs
  • Real test runners, real stack traces
  • Feature-extension prompts, not gotcha puzzles
  • Voice narration capture for mock reviews
Scenario: Exclusive Revenue · prefix/suffix2 failing tests
function totalExcludingEach(sales: number[]) {
  // TODO: make tests/pricing.spec.ts pass
  // Expected O(n), no division.
  return sales.map(() => 0);
}
FAILtests/pricing.spec.ts › handles single-row store
The whole loop · one subscription

Coding isn't enough. Neither are four subscriptions.

Most platforms ace one lane and punt the others. Alpha Code ships every lane with equal weight — priced to fit one budget.

Coding

  • Pattern-indexed catalog, not a 3,000-problem dump
  • Real IDE mode: debug a repo, not a puzzle box
  • Time-boxed drills with per-pattern diagnostics

System Design

  • Animated deep-dives: cache, queue, replica, shard
  • L5 → Staff+ tracks with scoped scenarios
  • ML-system design as a first-class lane, not an afterthought

Behavioral

  • STAR scaffolds tuned to scope, conflict, and ambiguity
  • Leadership-principle coverage without the cringe
  • Scenario banks for Staff, Principal, and EM loops

Mock Interviews

  • Live peer matching, no Outlook roulette
  • Voice-first: code while you narrate
  • Calibrated rubrics, not vibes-based feedback

One platform, whole loop

Stop stitching four subscriptions. Coding, system design, behavioral, and mocks live under one login.

Staff+ is the default, not an upsell

Scope trees, tech leadership, org-design prompts, and cross-functional scenarios ship in every plan.

Adaptive diagnostics that bite

Your dashboard reads: 'You fail sliding-window mediums under 20 minutes.' Then it schedules the fix.

ML / AI engineering track

Retrieval pipelines, eval harnesses, model-serving design, and LLM-system tradeoffs. Greenfield, covered.

Adaptive diagnostics

Your dashboard shouldn't lie to you.

Most platforms hand you a problem set and a pat on the back. We read your timing, pattern accuracy, and failure mode — then schedule the next drill against your actual weakness.

  • Per-pattern mastery, not a vanity streak
  • Time-to-insight measured alongside correctness
  • Honest verdicts — even the uncomfortable ones

Weekly diagnostic

2026-04-19
Sliding Window52% · Medium · > 20 min
Monotonic Stack81% · Solid
Union-Find38% · Cycle cases
Interval Sweep74% · Edge overlap
2-D DP46% · State design
Next drill: Pharmacy Pickup · variable sliding window · 18-minute time box.
ML / AI engineering track

The interview lane nobody else covers — shipped on day one.

Retrieval pipelines, eval harnesses, model-serving design, LLM system tradeoffs, and cost-shaped scaling. Written by engineers who actually ship these stacks.

  • Vector index choicescenario
  • Eval harness from scratchscenario
  • LLM routing under budgetscenario
  • Feature store shapescenario
Pricing · one tier, whole loop

One subscription. Every lane. No upsell tax.

Stacking four interview-prep subscriptions runs past $500/year. Alpha Code keeps it simple.

Free forever

$0/ forever

Enough to prove patterns work.

  • 30 pattern-indexed scenarios
  • Weekly diagnostic read-out
  • Community mock matching
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$19/ month

Everything. One login. Cancel any month.

  • Full pattern catalog + real-repo IDE mode
  • System design: L4 → Staff+
  • Behavioral scaffolds + scenario banks
  • Priority peer mocks with calibrated rubrics
  • ML / AI engineering track
  • Post-hire skill tracks (keep the login)
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Student pricing available. Annual plan billed at $180 / year. Enterprise seats on request.

Stop grinding. Start patterning.

One subscription. Twelve patterns. The full loop. Built for the engineer you're becoming, not the one answering trivia.

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