The O(n) Club: LRU Cache—Because Algorithms Have Bouncers
The O(n) Club: LRU Cache—Because Algorithms Have Bouncers ⚡ TL;DR Stop letting your cache become a digital landfill. The LRU (Least Recently…
The O(n) Club: Number of Matching Subsequences: Parading Your Words With Buckets, Not Regret
The O(n) Club: Number of Matching Subsequences — Parading Your Words With Buckets, Not Regret ⚡ TL;DR You get a string s and an array of…
The O(n) Club: Vertical Order Traversal of a Binary Tree: Columns, Chaos, and Why BFS Wins
The O(n) Club: Vertical Order Traversal of a Binary Tree — Columns, Chaos, and Why BFS Wins ⚡ TL;DR Want to print a binary tree column by…
The O(n) Club: Word Pattern—Where One-to-One Mapping Gets Real (and Painful)
The O(n) Club: Word Pattern—Where One-to-One Mapping Gets Real (and Painful) ⚡ TL;DR Given a pattern like “abba” and a string like…
The O(n) Club: Integer to Roman – How to Greedily Conquer Antiquity with Java
The O(n) Club: Integer to Roman – How to Greedily Conquer Antiquity with Java ⚡ TL;DR Need to translate boring numbers into Roman numerals for…
The O(n) Club: Roman to Integer — Why Does ‘IX’ Always Betray Me?
The O(n) Club: Roman to Integer — Why Does ‘IX’ Always Betray Me? ⚡ TL;DR Roman numerals aren’t just fancy birthday cake icing—they come…
The O(n) Club: LFU Cache: How to Get Unpopular Fast (and Still Write O(1) Java)
The O(n) Club: LFU Cache — How to Get Unpopular Fast (and Still Write O(1) Java) ⚡ TL;DR LFU (Least Frequently Used) Cache is basically a…
The O(n) Club: Isomorphic Strings — The Interview Trap That Snags Smart Devs
The O(n) Club: Isomorphic Strings — The Interview Trap That Snags Smart Devs ⚡ TL;DR Want to see if two strings can become each other by…
The O(n) Club: Two Sum IV – The BST Showdown You Didn’t Know You Needed
The O(n) Club: Two Sum IV – The BST Showdown You Didn’t Know You Needed ⚡ TL;DR Given a binary search tree and a target k, does any pair…
The O(n) Club: Jewels and Stones — HashSet Heroics for the Chronically Loopy
The O(n) Club: Jewels and Stones — HashSet Heroics for the Chronically Loopy ⚡ TL;DR You have a string of jewels (unique, case-sensitive,…