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: Fibonacci Number: Attack of the Useless Recursion
The O(n) Club: Fibonacci Number—Attack of the Useless Recursion ⚡ TL;DR If you’re asked for the nth Fibonacci number, please do not set your…
The O(n) Club: Power of Two — Bitwise Magic and the Ancient Single-Bit Prophecy
The O(n) Club: Power of Two — Bitwise Magic and the Ancient Single-Bit Prophecy ⚡ TL;DR Don’t know if your number is a power of two? Skip the…
The O(n) Club: Add Strings — When Java Says ‘No Cheating’, Do This
The O(n) Club: Add Strings — When Java Says ‘No Cheating’, Do This ⚡ TL;DR Add two monster-sized numbers given as strings. You…
The O(n) Club: Cracking Integer Sqrt(x) Like a (Java) Boss
The O(n) Club: Cracking Integer Sqrt(x) Like a (Java) Boss ⚡ TL;DR Don’t use Math.sqrt(). Don’t dare touch floats. Compute the…
The O(n) Club: All Possible Parentheses — Recursion Goes Wild
The O(n) Club: All Possible Parentheses — Recursion Goes Wild ⚡ TL;DR Given an expression like “2*3-4*5”, your job is to group…
The O(n) Club: Permutation Sequence: The Algorithmic VIP Pass
The O(n) Club: Permutation Sequence — The Algorithmic VIP Pass ⚡ TL;DR Find the k-th permutation (in lex order) of numbers 1 to n… without…
The O(n) Club: Stack Your Sanity with LeetCode 224’s Basic Calculator
The O(n) Club: Stack Your Sanity with LeetCode 224’s Basic Calculator ⚡ TL;DR Can you evaluate arithmetic strings with ‘+’,…
The O(n) Club: Exponentiation by Squaring in Java – Because Your CPU Has Feelings Too
The O(n) Club: Exponentiation by Squaring in Java – Because Your CPU Has Feelings Too ⚡ TL;DR If you’re still looping through n…
The O(n) Club: When String Calculators Attack (a.k.a. LeetCode 227, but Funnier)
The O(n) Club: When String Calculators Attack (a.k.a. LeetCode 227, but Funnier) ⚡ TL;DR Given a string with numbers and +, -, *, /, compute…