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Lessons (28)

• Python and Math Foundations with Runnable Examples

  … It is a geometric score, not a probability of correctness. python from math import sqrt def cosine(left …

• What to Learn in AI, and in What Order

  … 2. Math you can use: Learn vectors and matrices, probability, averages and variance, derivatives, and the idea of …

• Code Smells & Refactoring

  … return Math.PI shape.r 2; case "square": return shape.side 2; } } // ✅ Each shape knows how to compute …

• Dynamic Programming

  … coin of coins) { if (coin <= a) dp[a] = Math.min(dp[a], dp[a - coin] + 1); } } return dp …

• Two Pointers & Sliding Window

  … update best using the window [left, right] best = Math.max(best, right - left + 1); } return best; } How to …

• Structural Patterns: How to Connect Objects

  … Array.from({ length: 100 000 }, () = ({ x: Math.random() 1000, y: Math.random() 1000, type: getTreeType("oak", "oak.png …

• Binary Search

  … lo, hi] is not empty const mid = lo + Math.floor((hi - lo) / 2); if (sorted[mid] === target) return …

• Arrays & Strings

  … for (const n of nums) { min = Math.min(min, n); max = Math.max(max, n); sum += n; } return …

• DSA Interview Patterns Cheat Sheet

  … O(log n) or O(1) Binary search, math Example: intervals (merge overlapping meetings) js function mergeIntervals(intervals …

• Resilience Patterns

  … throw error; const backoff = Math.min(maxMs, baseMs 2 (attempt - 1)); const jitter = Math.random() backoff; // spread clients …

• Count, for_each, Functions, and Stable Identities

  … merge for tag maps, and cidrsubnet for subnet math. hcl locals { common tags = { ManagedBy = "Terraform", Team = "platform" } tags …

• Concurrency, Resilience & Distributed Workflows

  … const delay = Math.min(30 000, 250 2 attempt); const jittered = delay (0.5 + Math.random()); await sleep …

• JavaScript Language Fundamentals

  … Node.js also still supports the older CommonJS ( require ). js // math.js export const PI = 3.14159; export …

• O — Open/Closed Principle

  … number { const best = Math.max(0, ...this.rules.filter((r) = r.appliesTo(cart)).map((r) = r.discount(cart …

• L — Liskov Substitution Principle

  … Square extends Rectangle In maths, a square is a rectangle. So inheritance seems natural: js class Rectangle { setWidth …

• Developer Learning Plan and Document-Assistant Capstone

  … units Week 2 Vectors, probability, metrics Run the math exercises Calculate similarity, precision, and recall Week 3 Training …

• Trees & Binary Search Trees

  … empty tree return 1 + Math.max(height(node.left), height(node.right)); // combine } // Count nodes const count = (node …

• Heaps & Priority Queues

  … No node objects needed: For the node at index i Formula --- --- Parent Math.floor((i - 1) / 2) Left …

• A WhatsApp OTP Is Only Single Use If You Make It So

  … string { return randomInt(0, 1 000 000).toString().padStart(6, '0'); // CSPRNG, never Math.random() } function hashOtp(code …

• Big-O Notation Made Simple

  … m = -Infinity; for (const x of arr) m = Math.max(m, x); return m; } // O(n) space: builds …

• Frontend Testing Strategy

  … number }[], discount = 0) { const subtotal = items.reduce((sum, item) = sum + item.price item.qty, 0); return Math.round …

• Code Profiling

  … toSummaryRow); logger.info({ customerId, orderCount: orders.length, durationMs: Math.round(performance.now() - startedAt), }, "order summary completed"); return summary …

• TypeScript in Practice

  … Circle Square null) { if (shape === null) return 0; // equality narrowing if ("radius" in shape) return Math.PI shape …

• Behavioral Patterns II: Chain, Template, Iterator, Mediator, Memento, Visitor

  … yield song; } shuffled() { const copy = [...this.songs].sort(() = Math.random() - 0.5); yield copy; } } const playlist = new Playlist …

• Node.js and Express

  … console.log( ${req.method} ${req.originalUrl} ${res.statusCode} ${Math.round(performance.now() - start)}ms ); }); next(); }); // Route-level: only …

• Domain-Driven Design: Tactical Patterns

  … Money { return new Money(Math.round(this.cents factor), this.currency); } equals(other: Money) { return this.cents === other …

• Python Fundamentals

  … Threads release the GIL while waiting CPU-bound (math, image processing) multiprocessing / ProcessPoolExecutor Separate processes, separate GILs Heavy …

• Caching & Redis

  … max 100 requests per minute per user const key = rate:${userId}:${Math.floor(Date.now() / 60000)} ; const count …