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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
Coming soonPaid plan
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
Start free
Coming soon

Loop · planned

$19/ month (planned)

Not yet available. Join the waitlist for early access — no credit card, no charge.

  • 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)

The free tier is live today. Pricing for the paid Loop plan is provisional and the plan has not launched. We will not collect payment until launch.

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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