The O(n) Club: Divide Two Integers (Without /, *, or %? Madness!)
The O(n) Club: Divide Two Integers (Without /, *, or %? Madness!) ⚡ TL;DR Dividing integers in Java when division, multiplication, and modulo…
The O(n) Club: Cousins in Binary Tree: Sibling Rivalry—Algorithm Edition
The O(n) Club: Cousins in Binary Tree—Sibling Rivalry, Algorithm Edition ⚡ TL;DR If two nodes are at the same depth but have different…
The O(n) Club: Maximum Points You Can Obtain from Cards — Sliding Windows, Not Heart Attacks
The O(n) Club: Maximum Points You Can Obtain from Cards — Sliding Windows, Not Heart Attacks ⚡ TL;DR Grab k cards from either the start or end…
The O(n) Club: Trapping Rain Water II: How to Flood a 2D Matrix Without Crying
The O(n) Club: Trapping Rain Water II — How to Flood a 2D Matrix Without Crying ⚡ TL;DR This is the classic LeetCode problem where you…
The O(n) Club: Evaluate Reverse Polish Notation — Now With 100% More Stack and 200% Less Parentheses
The O(n) Club: Evaluate Reverse Polish Notation — Now With 100% More Stack and 200% Less Parentheses ⚡ TL;DR Evaluating expressions in Reverse…
The O(n) Club: Alien Dictionary: Sorting Out Topo-Sorted Antics
The O(n) Club: Alien Dictionary – Sorting Out Topo-Sorted Antics ⚡ TL;DR The aliens dumped a list of words in your inbox and expect you to…
The O(n) Club: Palindrome Pairs — Hashmaps, Not Hunches
The O(n) Club: Palindrome Pairs — Hashmaps, Not Hunches ⚡ TL;DR Find every unique pair of indices (i, j) in an array of words where words[i] +…
The O(n) Club: Combination Sum III, or: Picking K Numbers that Add Up, But Skip the Guilt
The O(n) Club: Combination Sum III, or: Picking K Numbers that Add Up, But Skip the Guilt ⚡ TL;DR Find every possible set of k unique numbers…
The O(n) Club: Serialize and Deserialize BST—Now With 50% Less Useless Data
The O(n) Club: Serialize and Deserialize BST—Now With 50% Less Useless Data ⚡ TL;DR Want to flatten a Binary Search Tree for storage or…
The O(n) Club: Open the Lock (LeetCode 752) — When BFS Is Literally All You Need
The O(n) Club: Open the Lock (LeetCode 752) — When BFS Is Literally All You Need ⚡ TL;DR You’ve got a 4-wheel lock (think: digital nightmare),…