The O(n) Club: Minimum Cost for Tickets (aka, The ‘Why Can’t I Just Be Greedy’ Problem)
The O(n) Club: Minimum Cost for Tickets (aka, The ‘Why Can’t I Just Be Greedy’ Problem) ⚡ TL;DR Given a random set of travel…
The O(n) Club: How to Actually Rebuild a Binary Tree from Inorder and Postorder (Without Crying)
The O(n) Club: How to Actually Rebuild a Binary Tree from Inorder and Postorder (Without Crying) ⚡ TL;DR Given two arrays (inorder,…
The Mutex Club: Building Bulletproof Job Schedulers with Smart Retries
Key Insights – Building a Job Scheduler with Retry # Balancing Reliability and Resources A modern job scheduler—whether you’re wiring up n8n,…
The Mutex Club: Mastering Java Parallel Merge Sort with ForkJoinPool
Key Insights # Divide and Conquer with ForkJoinPool ForkJoinPool is Java’s answer to your recursive parallel fantasies. It splits your array…
The O(n) Club: Majority Element II and the Pigeonhole Plot Twist
The O(n) Club: Majority Element II and the Pigeonhole Plot Twist ⚡ TL;DR Need to spot every array element that appears more than n/3 times?…
The O(n) Club: Permutation in String — Where Brute Force Goes To Die
The O(n) Club: Permutation in String — Where Brute Force Goes To Die ⚡ TL;DR Given two strings, does s2 have a substring that’s a…
The Mutex Club: Mastering Singletons, Thread Safety & Double-Checked Locking
Key Insights # One Instance Only The singleton pattern guarantees a single class instance and global access. It’s ideal for loggers,…
The Mutex Club: How Semaphore-Based Rate Limiters Actually Work (and Why They’re More Than Just Fancy Locks)
Semaphore Rate Limiting: The Velvet Rope for Your Threads Ever felt like your backend needed a bouncer? Enter semaphores. While mutexes get…
The O(n) Club: Reorganize String (Or How to Avoid Awkward Repeats)
The O(n) Club: Reorganize String (Or How to Avoid Awkward Repeats) ⚡ TL;DR Your string is throwing a party, but it can’t have two guests…
The O(n) Club: Why Splitting Arrays Feels Like Filing Taxes (LeetCode 410 Explained)
The O(n) Club: Why Splitting Arrays Feels Like Filing Taxes (LeetCode 410 Explained) ⚡ TL;DR You’ve got a rowdy array, and you want to…