Search

Lessons (30)

• Sorting Algorithms

  From simple bubble sort to merge sort and quick sort. See how each one works, compare their speeds …

• Two Pointers & Sliding Window

  … pair with target sum (sorted array) js function pairWithSum(sorted, target) { let left = 0; let right = sorted.length …

• Binary Search

  Find anything in a sorted list of a billion items in about 30 steps. Learn the classic algorithm …

• DSA Interview Patterns Cheat Sheet

  … decision flowchart mermaid flowchart TD S([Read the problem]) -- A{Input sorted,<br/ or 'find in sorted'?} A …

• Indexes, EXPLAIN & Query Plans

  Design indexes from real filter, join and sort patterns, then prove improvements with query plans and production-like …

• Big-O Notation Made Simple

  … the problem is cut in half every step function binarySearch(sorted, target) { let lo = 0, hi = sorted.length …

• Heaps & Priority Queues

  … Top K ⭐ "Find the k largest numbers in a stream of a million numbers." Sorting is O(n …

• Arrays & Strings

  … Iterate backwards or use filter . - sort() sorts as strings by default: [10, 9, 1].sort() → [1, 10, 9 …

• Database Indexing & Transactions

  … Because the keys are sorted , B-trees also make ORDER BY , BETWEEN and / < fast. Creating and checking indexes …

• Trees & Binary Search Trees

  … Root → Right 4, 2, 5, 1, 3 BST → sorted order Post-order Left → Right → Root 4, 5, 2 …

• Graphs: BFS & DFS

  … path, nearest X, levels Cycles, connected components, topological sort, mazes, backtracking Both run in O(V + E) : every …

• SQL Interview Query Drills

  … Ask whether the interviewer instead wants one row or the third row after sorting; the query differs.

• Consumers & Consumer Groups

  … A team can split the pile so each person takes a few mail bags, and nobody sorts the …

• SQL Language, Identifiers & Data Types

  … UNION vs UNION ALL UNION removes duplicates, usually with sort/hash work. UNION ALL returns every row and …

• N+1 Queries, Loading & Pagination

  … it with an index matching the filter and sort, such as orders(customer id, created at DESC, id …

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

  … You use it every time you write: js users.sort((a, b) = a.age - b.age); // sorting strategy …

• REST API Design

  … Paginate, filter and sort lists Never return an unbounded list; one day it will be a million rows …

• Caching & Redis

  … recent activity Set SADD , SISMEMBER Unique visitors, tags Sorted set ZADD , ZRANGE , ZREVRANK Leaderboards , priority queues, time windows …

• What Are Design Patterns?

  … use(middleware) in Express Chain of Responsibility array.sort((a, b) = a - b) Strategy for (const x of …

• Comments & Formatting

  … help Type Example --- --- Why (a decision) // Use insertion sort: lists here are always < 10 items and it's …

• Meaningful Names

  … a short loop or (a, b) in a sort comparator. Rule 4: One word per concept Pick one …

• Hash Maps & Sets

  … for (const word of words) { const key = [...word].sort().join(""); // "eat" → "aet" if (!groups.has(key)) groups.set …

• Linked Lists

  … front removes that special case. js // Merge two sorted lists: 1→3→5 + 2→4 → 1→2→3 …

• Pods

  … sh shell inside the container kubectl get events --sort-by=.lastTimestamp mermaid flowchart TD P{Pod not healthy …

• SQL vs NoSQL Databases

  … ISODate("2026-09-28T10:00:00Z") } db.orders.find({ "customer.email": "ana@mail.com" }).sort({ createdAt: -1 }); 💡 Model …

• Kafka Producers

  … A postal worker doesn't drive to the sorting office for every single letter. They collect letters in …

• CQRS & Event Sourcing

  … req.user.id }).sort({ placedAt: -1 })); }); The catch: eventual consistency The read model updates a moment after the …

• Helm, kubectl Cheat Sheet & Best Practices

  … kubectl top nodes Recent events kubectl get events --sort-by=.lastTimestamp Dry run + diff kubectl diff -f app …

• React Hooks in Practice

  … remember expensive things jsx // Remember an expensive calculation until its inputs change const sortedProducts = useMemo( () = products.toSorted((a …

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

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