Array

The O(n) Club: Best Time to Buy and Sell Stock with a Transaction Fee (Or, How to Not Get Fleeced by the Middleman) ⚡ TL;DR Maximize stock…

The O(n) Club: The Skyline Problem — Heap, Sweep, and the Art of Urban Java ⚡ TL;DR Given a row of buildings, your job is to chart those…

The O(n) Club: Two Oddballs, One XOR Trick – Solving Single Number III Without the Hashmap Hype ⚡ TL;DR You’ve got an int array where…

The O(n) Club: Single Number II—That One Rogue Bit Nobody Likes ⚡ TL;DR Given an array where every number appears three times except one…

The O(n) Club: Contiguous Array—Find Your Zen Between 0s and 1s ⚡ TL;DR Want the longest streak where your array plays fair and tallies the…

The O(n) Club: Find K Closest Elements and Avoid Interviewer Ambushes ⚡ TL;DR If you’re asked for k elements closest to x in a sorted array,…

The O(n) Club: How to Handle Array Doppelgängers Without Losing Your Sanity ⚡ TL;DR This is that magical Leetcode problem where duplicates…

The O(n) Club: Max Consecutive Ones III—Where Sliding Windows Beat Your WiFi and Your Bugs ⚡ TL;DR Want to binge 1s in your binary array by…

The O(n) Club: Dungeon Game – Save Your Knight, Your Code, and Your Sanity ⚡ TL;DR You’ve got a grid of rooms, each giving or stealing…

The O(n) Club: Surviving Interval List Intersections Without Meltdowns ⚡ TL;DR Need to intersect two sorted, non-overlapping interval lists in…