The O(n) Club: Range Sum Query – Mutable (Or Why Prefix Sums Need Therapy)
The O(n) Club: Range Sum Query – Mutable (Or Why Prefix Sums Need Therapy) ⚡ TL;DR If you want fast range sums and in-place updates,…
The O(n) Club: Unique Paths III and the Roomba That Never Misses a Spot
The O(n) Club: Unique Paths III and the Roomba That Never Misses a Spot ⚡ TL;DR Pathfinding? Easy. Pathfinding without leaving a single square…
The O(n) Club: Ones and Zeroes: Binary Knapsack and the Joy of Resource Regret
The O(n) Club: Ones and Zeroes — Binary Knapsack and the Joy of Resource Regret ⚡ TL;DR Your mission: select the most binary strings possible…
The O(n) Club: Arithmetic Slices: Why Your Loops Are Weeping (And How to Fix Them)
The O(n) Club: Arithmetic Slices — Why Your Loops Are Weeping (And How to Fix Them) ⚡ TL;DR Count all contiguous subarrays (length 3+) where…
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: Find Minimum in Rotated Sorted Array II: The Binary Search Headache That Won’t Quit
The O(n) Club: Find Minimum in Rotated Sorted Array II – The Binary Search Headache That Won’t Quit ⚡ TL;DR Got a sorted array, spun…
The O(n) Club: The Shortest Subarray with Sum at Least K (When Negatives Sabotage Everything)
The O(n) Club: The Shortest Subarray with Sum at Least K (When Negatives Sabotage Everything)
The O(n) Club: Delete Nodes and Return Forest – Chainsaw Edition
The O(n) Club: Delete Nodes and Return Forest – Chainsaw Edition ⚡ TL;DR Delete designated nodes from your binary tree, then collect the roots…
The O(n) Club: Reverse Bits—When Your Integers Stage a Flash Mob
The O(n) Club: Reverse Bits—When Your Integers Stage a Flash Mob ⚡ TL;DR We’re flipping every bit in a 32-bit number. Take the far right bit,…
The O(n) Club: Fibonacci Number: Attack of the Useless Recursion
The O(n) Club: Fibonacci Number—Attack of the Useless Recursion ⚡ TL;DR If you’re asked for the nth Fibonacci number, please do not set your…