Array

The O(n) Club: Maximum Length of Pair Chain—The Greedy Way to Outsmart Your Calendar (and Interviewer) ⚡ TL;DR This problem is like scheduling…

The O(n) Club: Number of Good Pairs – Because Nested Loops Deserve Retirement ⚡ TL;DR Count (i, j) with nums[i] == nums[j] and i <…

The O(n) Club: Can Place Flowers—Or How to Not Plant a Bug Farm ⚡ TL;DR You’ve got a 0-1 array (flowerbed), a number n, and a simple dream:…

The O(n) Club: Contains Duplicate II, Because Sometimes Your Bugs Are Neighbors ⚡ TL;DR You’re not hunting for ordinary duplicates;…

The O(n) Club: Find Common Characters — Where Duplicate Letters Are Finally Invited ⚡ TL;DR Want every letter that appears in all strings,…

The O(n) Club: Shortest Distance to a Character — Why Single Pass Devs Cry Twice ⚡ TL;DR You want the minimum distance from every index in a…

The O(n) Club: Sliding Window Buckets and the Art of Almost-Duplicates (LeetCode 220) ⚡ TL;DR Don’t want to wreck your runtime with…

The O(n) Club: Shortest Bridge — When DFS and BFS Join Forces (and Regret It Immediately) ⚡ TL;DR Connect two islands in a binary grid by…

The O(n) Club: Pascal’s Triangle II, or How to Mutate Arrays Without Crying ⚡ TL;DR Pascals’s Triangle II: You want rowIndex-th row (0-based)…

The O(n) Club: Frog Jump — Can Your Recursion Swim, or Will It Croak? ⚡ TL;DR Frog at stone 0 wants to land on the last stone, only jumping…