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The O(n) Club: Best Time to Buy and Sell Stock: Because Margins and Caffeine Can Only Do So Much ⚡ TL;DR One shot at glory: buy low, sell…

The O(n) Club: Rotated Binary Search Mania (feat. Dizzy Arrays & Java) ⚡ TL;DR Sorted array had a quarter-life crisis and rotated, but you…

The O(n) Club: Longest String Chain — The Interview Jenga That Breaks Spirits ⚡ TL;DR Find the biggest possible chain where each word is built…

The O(n) Club: Subarray Minimums & The Stack That Outsmarts Brute Force ⚡ TL;DR Want to sum up the minimum of every contiguous subarray?…

The O(n) Club: Counting Squares in Binary Matrices (Because Rectangles Are for Quitters) ⚡ TL;DR Counting all squares (not just the “big…

The O(n) Club: Detecting 132 Patterns Faster Than Your Interviewer Can Blink ⚡ TL;DR Find three numbers in an array that say, “Look, I zigged…

The O(n) Club: Delete and Earn – When House Robber Goes Full Arcade ⚡ TL;DR Every time you delete a number, you also assassinate its…

The O(n) Club: Largest Divisible Subset—DP, Java, and Chaos Prevention ⚡ TL;DR This problem is basically “who can divide whom at the nerd…

The O(n) Club: Pacific Atlantic Water Flow’s Reverse-DFS Party Trick ⚡ TL;DR Which cells in a height matrix can get their water to both…

The O(n) Club: Asteroid Collision—Simulate, Stack, Survive (LeetCode 735) ⚡ TL;DR Bunch of asteroids, each moving left or right. When they…