The O(n) Club: Longest Palindrome – How to Build One Without Breaking a Sweat
The O(n) Club: Longest Palindrome – How to Build One Without Breaking a Sweat ⚡ TL;DR This isn’t “is it a palindrome?” country —…
The O(n) Club: Validate Stack Sequences: Because Stack Cheating Isn’t a Sport
The O(n) Club: Validate Stack Sequences — Because Stack Cheating Isn’t a Sport ⚡ TL;DR Given two lists—one is the push parade, the other is…
The O(n) Club: Intersection of Two Arrays: When HashSets Save Your Sanity (and Your CPU)
The O(n) Club: Intersection of Two Arrays — When HashSets Save Your Sanity (and Your CPU) ⚡ TL;DR You want all unique elements from both…
The O(n) Club: When Prime Factors Make You a Copy-Paste Ninja (2 Keys Keyboard)
The O(n) Club: When Prime Factors Make You a Copy-Paste Ninja (2 Keys Keyboard) ⚡ TL;DR You have two buttons and a dream: Copy All and Paste.…
The O(n) Club: The 2D Prefix Sum – Stop Hating Matrix Math (and Yourself)
The O(n) Club: The 2D Prefix Sum – Stop Hating Matrix Math (and Yourself) ⚡ TL;DR Quit writing those nested loops for every sum in a matrix.…
The O(n) Club: Remove All Adjacent Duplicates in String II—Stack Attack Edition
The O(n) Club: Remove All Adjacent Duplicates in String II—Stack Attack Edition ⚡ TL;DR Input: string + integer k. Goal: keep destroying any…
The O(n) Club: Two City Scheduling: Greed, Sorting, and Not Getting Yelled At By Accounting
The O(n) Club: Two City Scheduling—Greed, Sorting, and Not Getting Yelled At By Accounting ⚡ TL;DR Got an even number of people and two…
The O(n) Club: Sum of Distances in Tree — Two DFSes, No Tears
The O(n) Club: Sum of Distances in Tree — Two DFSes, No Tears ⚡ TL;DR Want to sum distances from every node to every other node? Don’t…
The O(n) Club: Reverse Pairs & That Merge Sort Plot Twist
The O(n) Club: Reverse Pairs & That Merge Sort Plot Twist ⚡ TL;DR LeetCode 493 asks: How many index pairs (i, j) have i 2 * nums[j]?Brute…
The O(n) Club: Excel Sheet Column Title — The “A-Z” That Breaks Brains
The O(n) Club: Excel Sheet Column Title — The “A-Z” That Breaks Brains ⚡ TL;DR Turn a number into Excel’s loopy column…