Articles, Case Studies & Insights
Faisal Affan
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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.
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.
Every Role I've Played — Junior to CTO, What I Actually Did at Each Level
A candid career retrospective tracing my journey through every engineering role: Junior developer grinding through fundamentals, Mid-level shipping production features, Senior designing architectures, Staff building org-wide leverage, and CTO-level strategic decisions. Each section maps to the portfolio strategy framework with real projects, real metrics, and real lessons.
What I Did at the CTO Level — Business Strategy Through Technology
At this level, your portfolio isn't about technology — it's about how technology created business value. I reduced AI inference costs by 90%, built an MCP orchestration that 3x'd developer output, and established a FOSS strategy where every repo is a 24/7 portfolio asset. This is what engineering leadership actually delivers.
What I Did as a Junior Developer — The Fundamentals That Shaped Everything
No production experience. GitHub full of tutorial repos. One asset: the ability to learn fast and zero fear of breaking things. This is what I actually built as a junior engineer — WordPress sites, a PHP university system, and the hardcoded credentials mistake that taught me security forever.
What I Did as a Mid-Level Engineer — Shipping, Ownership & Production Scars
I shipped real features to real users. I broke production and fixed it alone at 2 AM. I built a mobile banking app with 680K downloads, a mining fleet system saving $200K/year, and a field operations platform for 4.1M users. This is what mid-level engineering actually looks like — the projects, the metrics, and the production incidents that made me a real engineer.
