The O(n) Club: Happy Number — When Integers Need Therapy
The O(n) Club: Happy Number — When Integers Need Therapy ⚡ TL;DR Take a number. Replace it with the sum of the squares of its digits. Repeat.…
The O(n) Club: Pascal’s Triangle — Why Is Everything a 1?
The O(n) Club: Pascal’s Triangle — Why Is Everything a 1? ⚡ TL;DR Pascal’s Triangle is that legendary integer pyramid where each number…
The O(n) Club: Clone Graph (LeetCode 133) Without Spawning Infinite Twins
The O(n) Club: Clone Graph (LeetCode 133) Without Spawning Infinite Twins ⚡ TL;DR You’ve got a connected undirected graph, and you need to…
The O(n) Club: Evaluate Division – Connect the Dots, Multiply the Drama
The O(n) Club: Evaluate Division – Connect the Dots, Multiply the Drama ⚡ TL;DR Take some equations like a / b = 2.0, make a directed,…
The O(n) Club: House Robber II: When Your Path Turns Circular (and Paranoid)
The O(n) Club: House Robber II—When Your Path Turns Circular (and Paranoid) ⚡ TL;DR Old problem: Rob a line of houses, don’t trip two neighbor…
The O(n) Club: Longest Palindromic Subsequence: Where Dynamic Programming Eats Exponential Time For Breakfast
The O(n) Club: Longest Palindromic Subsequence — Where Dynamic Programming Eats Exponential Time For Breakfast ⚡ TL;DR Given a string,…
The O(n) Club: Missing Number — How to Outsmart That One Number Who Didn’t RSVP
The O(n) Club: Missing Number — How to Outsmart That One Number Who Didn’t RSVP ⚡ TL;DR One number from to n ditched your array —…
The O(n) Club: Delete Node in a BST — When Trees Demand Therapy
The O(n) Club: Delete Node in a BST — When Trees Demand Therapy ⚡ TL;DR Deleting a node in a BST is three things: drama-free for leaves,…
The O(n) Club: Subtree of Another Tree: How to Find Doppelgänger Branches (and Not Lose Your Mind)
The O(n) Club: Subtree of Another Tree – How to Find Doppelgänger Branches (and Not Lose Your Mind) ⚡ TL;DR Want to know if subRoot is…
The O(n) Club: Queue Reconstruction by Height is Just Tall-Tale Sorting
The O(n) Club: Queue Reconstruction by Height is Just Tall-Tale Sorting ⚡ TL;DR You get a list of [height, k] for people—k means “number of…