Two pointers: turning O(n²) scans into one pass
Two indexes moving with a purpose can replace nested loops. The trick is knowing which pointer to move and why it is safe to skip what you skip.
WRITING / NOTES FROM THE FORGE
Interviews
8 articles tagged Interviews.
SQL Window Functions Explained With Practical Examples
SQL window functions explained with runnable examples: ROW_NUMBER vs RANK, LAG and LEAD, running totals, moving averages, and the ROWS vs RANGE frame trap.
Binary search is a decision rule, not a trick
Once you see binary search as "find the first place a condition becomes true", a whole family of interview problems collapses into one template.
Feeds at scale: when to push, when to pull
Fan-out on write makes reads instant until one account has fifty million followers. Here is how to reason about the hybrid most real feeds use.
How to Prepare for Coding Interviews: A 12-Week Roadmap
How to prepare for coding interviews in 12 weeks: a week-by-week plan for data structures, patterns, mock interviews, and communicating clearly under pressure.
What Happens When You Type a URL Into Your Browser?
What happens when you type a URL, step by step: DNS lookup, TCP or QUIC, TLS handshake, HTTP request, CDN, server work, and browser rendering explained.
Dynamic Programming for Beginners: A Step-by-Step Method
Dynamic programming for beginners: a repeatable five-step method to define state, write the recurrence, and move from memoization to tabulation with code.
System Design Interview Guide: A Step-by-Step Framework
A practical system design interview framework: clarify requirements, estimate scale, define APIs and data, sketch the design, then go deep on trade-offs.