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Best Time to Buy and Sell Stock: From Brute Force to One-Pass O(n)
Master the classic coding interview problem 'Best Time to Buy and Sell Stock' with step-by-step explanation — from the naive brute force approach, recognizing patterns, to the optimal one-pass O(n) solution using sliding window / two-pointer technique. Complete with array visualization, complexity analysis, and the intuition behind every decision.
6/19/2026
News
Integer to Roman: The Greedy Mapping That Always Shows Up in Interviews
Breaking down the integer to Roman numeral conversion problem — from basic Roman numeral rules, the subtractive notation pitfalls (IV, IX, XL...), to a clean, interview-ready greedy O(1) solution. Complete with mapping table, step-by-step visualization, and why this approach is optimal given the 1-3999 constraint.
6/19/2026
News
Portfolio Strategy by Career Level — Junior to CTO
Your portfolio should reflect your seniority level, not just list every project you've touched. Junior engineers sell potential and fundamentals. Senior engineers sell depth and architecture. Staff engineers sell leverage. CTOs sell business outcomes. Here's exactly what to put in your portfolio at each level — with concrete examples and a universal format you can use today.
6/13/2026
News
Services I've Handled — Full-Stack Engineering, Architecture & Product Strategy
A comprehensive list of professional services I've delivered across multiple industries: IoT fleet management, fintech core banking integration, cyber insurance platforms, education technology, and enterprise digital transformation. Each service backed by real production systems still running today.
6/13/2026
News
Modern AI Architecture: End-to-End
From the first user query to the response stored in the database. A complete guide to layers, tools, request flow, learning roadmap, and real-world production implementation — including the newly released Google ADK.
5/28/2026
News
97% of Websites Fail Accessibility Tests — Here's What You're Doing Wrong
Most developers think accessibility is 'not urgent' until they get sued. Learn WCAG 2.2, POUR principles, and implementation techniques you can apply immediately before your digital presence becomes a legal nightmare — and more importantly — a human failure.
4/1/2026
News
Claim to Be an 'AI-Driven Founder' But Build Using Local LLMs? Sorry, That's Just Playing House.
Some founders proudly build products from scratch using Ollama on a Rp 50 million PC. We break down why that's delusion, not innovation — and why a Rp 320k/month subscription is far more sensible.
3/19/2026
News
20 Database Problems That Make Senior Engineers Break a Cold Sweat in Production
N+1 is just the tip of the iceberg. Beneath it lie Cartesian Explosion, Lost Update, God Table, Replication Lag, ORM Trap, and 15 other far more dangerous problems — complete with real-world case studies and Golang solutions.
3/18/2026
News
OpenSpec: Stop 'Vibe Coding', Give AI a Clear Roadmap
Vibe Coding is like asking a contractor to build a house without a blueprint — the result? Chaos by the third month. OpenSpec arrives as an 'architectural blueprint' for AI coding, shifting the paradigm from random chatting to structured Spec-Driven Development.
3/15/2026
News
MCP: The Protocol That Lets AI Talk Directly to Your Database, Firebase, and Grafana
Model Context Protocol (MCP) is an open standard connecting LLMs with external data and tools — like USB-C for AI. Learn the architecture, how it works, and my real-world setup: 11 MCP servers from MySQL, Firebase, Grafana LGTM, to Lighthouse.
3/9/2026
News
Why I Ditched Rust, Node, and Python for Go: The Brutally Honest Benchmark Data
A head-to-head benchmark of 7 popular programming languages: performance, memory, concurrency, developer experience, and the hiring market. Discover exactly why Go dominates production at millions of requests — and why I almost jumped ship to Rust (but didn't).
3/1/2026
News
Stop Being a Code Monkey: Why Business-Savvy Developers Earn 3x More
Are you 'just' working on Jira tickets while other developers are shaping product decisions and leveling up 3x faster? Here is the framework that transformed me from a regular backend engineer into someone who owns business outcomes — with real-world production examples.
2/19/2026