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Lessons (38)

• Trees & Binary Search Trees

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

• Kubernetes Cluster Architecture

  … store 3 Pods (no node yet) S- A: watch: unscheduled pods → pick nodes → bind pod to node 2 …

• Linked Lists

  A chain of nodes where each node points to the next. Learn how they differ from arrays, and …

• Graphs: BFS & DFS

  … node → nodes that depend on it const visited = new Set(), order = []; const visit = (node) = { if (visited.has(node …

• Backend Languages: Node.js, Go, Python & Rust

  … no garbage collector, no null pointer crashes. Popular frameworks Language Minimal Batteries included --- --- --- Node.js Express, Fastify, Hono …

• Scaling & Health Probes

  … add 1 node Cloud-- S: new node ready S- S: schedule the 2 Pending pods ✅ Staying available during …

• Docker & Containers

  … small and secure ---- FROM node:22-alpine WORKDIR /app ENV NODE ENV=production COPY package.json package-lock …

• Pods

  … created, waiting for a node / image pull Pending -- Running: scheduled and containers started Running -- Succeeded: all containers exited …

• Caching, Consistent Hashing and Sharding

  … A hash ring moves only some keys when nodes change. Choose a stable shard key such as tenant …

• ConfigMaps, Secrets & Storage

  … when a pod is deleted or moves to another node, everything written inside its filesystem is gone. That …

• Services & Ingress

  Pods come and go, so how does traffic find them? ClusterIP, NodePort and LoadBalancer Services, cluster DNS, Ingress …

• Deployments, ReplicaSets & Rollouts

  … log-agent"] n1["node-1: agent"] n2["node-2: agent"] n3["node-3: agent"] end yaml apiVersion: batch …

• SQL vs NoSQL Databases

  … scale OUT"] H1[Node 1] H2[Node 2] H3[Node 3] H4["+ Node 4"] end NoSQL databases like …

• Observability: Logs, Metrics & Traces

  … js) import { NodeSDK } from "@opentelemetry/sdk-node"; import { getNodeAutoInstrumentations } from "@opentelemetry/auto-instrumentations-node"; new NodeSDK({ instrumentations: [getNodeAutoInstrumentations …

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

  … right)} , }; const walk = (visitor) = function visit(node) { return visitor[node.type](node, visit); }; const expression = add(num(2 …

• Helm, kubectl Cheat Sheet & Best Practices

  … context --current --namespace=team-shop Drain a node kubectl drain <node --ignore-daemonsets 💡 Handy tools: k9s (a terminal …

• React Hooks in Practice

  … memory ( useState ), side effects ( useEffect ), references to DOM nodes ( useRef ) and more. They let small functions do what …

• Distributed Coordination: Consensus, Heartbeats and Gossip

  … or Paxos-style consensus Majority agreement Is a node probably alive? Heartbeat + timeout Suspicion, not certainty Spread membership …

• Heaps & Priority Queues

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

• What Is Apache Kafka?

  … They don't affect each other. A first taste (Node.js with KafkaJS) js import { Kafka } from "kafkajs …

• React Fundamentals

  … update only the changed text node State rules 1. Never mutate state directly. Create a new value. jsx …

• REST vs GraphQL vs gRPC

  … and server code in Go, Java, Node.js, Python… js // Node.js client (generated stubs make it feel …

• Message Queues & RabbitMQ

  … producer and consumer (Node.js, amqplib) js // producer.js import amqp from "amqplib"; const connection = await amqp.connect …

• Scaling, Load Balancing & Rate Limiting

  … requests/second average (peak maybe 5–10×) One Node.js / Go server Hundreds to thousands of simple requests …

• Caching & Redis

  … Hot key One key (a celebrity's profile) gets so much traffic it overloads a single Redis node …

• Why Kubernetes?

  … restarted automatically A server dies Manually move its containers elsewhere Rescheduled onto healthy nodes Traffic spikes 10× Manually …

• How a Web Request Works

  … logic] -- Rp[Repository] -- DB[(Database)] js // A minimal Node.js (Express) endpoint app.get("/products/:id", async (req …

• How Browsers Render a Page

  … builds the Document Object Model , a tree of nodes that JavaScript can read and change. html <body <header …

• JavaScript Essentials: Event Loop, Closures & this

  … function at a time Web APIs (browser) / libuv (Node) Oven, timer, delivery driver Do slow work in the …

• Kafka vs RabbitMQ & the Kafka Ecosystem

  … High (tens of thousands of msgs/s per node) Very high (millions of msgs/s per cluster) Consumer …

• Behavioral Patterns I: Observer, Strategy, Command, State

  … later, no edits)"] You've used it: addEventListener , Node's EventEmitter , RxJS, Redux store.subscribe , React state → re …

• TypeScript Essentials

  … br/ plain JavaScript"] JS -- Run[Runs in browser / Node] Types exist only at compile time . They're erased …

• DSA Interview Patterns Cheat Sheet

  … at the end · \ \ when you already hold the node What input size allows n up to… Target complexity …

• Kafka Producers

  … Without it, a retried batch could land after a later batch. Producing from Node.js (KafkaJS) js import …

• Deploying & Operating Microservices

  … an on-call rotation js // Graceful shutdown in Node.js process.on("SIGTERM", () = { server.close(async () = { // stop accepting …

• Serverless Architecture

  … warm calls reuse them), choose fast-starting runtimes (Node, Go, Rust), use provisioned concurrency for latency-critical paths …

• Sorting Algorithms

  … What does JavaScript's sort() use? V8 (Chrome, Node.js) uses TimSort : a hybrid of merge sort and …

• Database Indexing & Transactions

  … Each node holds many keys, so even a billion rows fit in a tree only 3–4 levels …