Sandbox Posts

Antiparallel 12-hour Clock Hands Print each of the 11 times, one per line, in the I:M:S format, at which the hour and minute hands of a 12-hour clock are antiparallel. Here I is the two digit hour, with 12 in place of 0; M is the two digit minute, and S is the truncated seconds value. The output ...

Recently, in an Analysis class, I was tasked with proving that the dyadic rationals are dense in R (which can be proven by the archimedean property). The dyadic rationals are defined as: $$\left\{ \dfrac{m}{2^n} \; | \; m \in \mathbb{Z},\; n \in \mathbb{N} \right\}$$ Your Goal: for two real numbe...

Count collisions in a python dictionary hashing python code-golf Task Given a list of integers as input, simulate Python's dictionary insertion process and count the total number of collisions that would occur. The process works as follows: Start with a hash table of size 8 For each number in th...

DeepBleak This challenge is about probing the limits of an LLM's reasoning skills. The basic idea is to create short DeepSeek prompts that produce long bodies of reasoning text and an objectively incorrect answer. More precisely: Participating Create a DeepSeek account (it's free). Start a new c...

Description: TODO Input: 01 matrix Output: Least horizon+vertical lines added to connect everything Test cases: (@=island, .=add hint) @@@ @ . => 1 @ @ @@@@ . => 1 @@ . .@@@@@ @ . @ . => 2 @ @@ ......... . .@@@@@

N-Step pyramid calculator. Calculate the number of blocks per column of an N step pyramid built using Y block, and return the number of blocks per column in a list. The build must use every single block, even if the result is an lopsided pyramid. The blocks can be placed in the right columns fir...

fastest-code Can you beat numpy convolve? The task is to compute the convolution of an array with itself as quickly as possible. The array will contain 80-bit extended precision long doubles and I will specify how the array is to be created. In order to get a good range the values will be sample...

Snakes on a 2xN grid code-golf A snake is defined as a consecutive ordering of a two dimensional grid which touches each square without jumps, starting at the square (0, 0). Below is an example of one snake of a 4x3 grid: 0 1 2 3 7 6 5 4 8 9 10 11 For any positive integer N, there are N s...

Decide Equality of Closed Surfaces Objective Given two closed surfaces (a.k.a. 2-manifolds), decide whether they're homeomorphic. Introduction In layman's terms, a closed surface is a shape that resembles a flat plane everywhere (say, when magnified very much). Familiar examples of a closed surfa...

Find the boolean logic to check if a number is prime! fastest-code primes binary integers Your task is to find a boolean expression that uses AND (\$\land\$), OR (\$\lor\$), XOR (\$\oplus\$), and NOT (\$\lnot\$) operators and binary digit positions (\$d_1,d_2,d_3,d_4,d_5,d_6,d_7,d_8,d_9,d_{10},\c...

Draw U+30EDE Biangbiang noodles are a type of Chinese noodle originating from Shaanxi cuisine. The noodles, touted as one of the "eight curiosities" of Shaanxi (陕西八大怪), are described as being like a belt, owing to their thickness and length. Biangbiang noodles are renowned for being written usin...

PizzaTian is a popular restaurant specializing in pizza delivery. Customers can place orders by phone, and each order comprises two components: Pizza Prices: The cost of each individual pizza. Delivery Fee: A fixed fee per order, regardless of the number of pizzas. Recently, PizzaTian has intro...

Parse a dollcode Challenge Dollcode is a trinary encoding system for numbers and text using unicode block drawing characters. The encoding scheme is defined as such (from the website): Numbers are encoded by looping through and checking each modulus 3 result, then replacing it with one of the th...

Cell`s Life #2: Infinite \$\color{crimson}{\text{META: this seems excessive? maybe stick to 100x100 boards or something similar}}\$ In the process of editing this right now so please do not upvote/downvote \$\color{crimson}{\text{Scoring (META)}}\$ \$\color{crimson}{\text{I have no clue what to p...

[DRAFT] Contained poker hands code-golf Input: A 5-card poker hand Output: All hands contained within the input. If hand appears multiple times, only output once. order does not matter list of poker hands

Index into a Fibonacci tiling The Cartesian plane can be tiled with increasingly large squares like so: This tiling can be generated by starting with a square of side length 1, placed at the origin 0, 0, and then repeatedly adding a square to the side of the resulting rectangle clockwise of the ...

Next Prime from Previous Primes Challenge Prime numbers are at the heart of mathematics, yet generating them typically requires sieves, searches, or direct primality testing. But what if we could predict the next prime purely mathematically, using only the primes that came before it? Your task is...

The steps of sorting a stack of disks on three pegs You have a Tower of Hanoi-esque set of 3 pegs, labelled A, B, C. There is a stack of unsorted disks from 1 to n on peg A. The only move allowed is to move the top k disks from a peg to another peg. You may not take disks from the middle of the s...

Card-Jitsu Part 1: Find all winning sets of three cards code-golfcard-gamecombinatorics Card-Jitsu was a mini card-game based on Rock, Paper, Scissors available on the children-focused online game "Club Penguin". I first wrote a challenge where you needed to implement a clone of this game, but I ...

Number of legal position in 1D go A 1D go position on a board of size n is a sequence of length n consisting of the numbers0, 1, 2. Not all numbers need to appear in the sequences. A sequence is legal if every block of 1's has a 0 next to it and every block of 2's has a 0 next to it. Think of 1 a...

Shuffle a deck of cards without bending them My brother plays the card game Magic: The Gathering. Apparently, the cards can be pretty expensive, so in order to keep them in Pristine Condition™, he has a special strategy for shuffling his deck without the cards getting damaged. Figure 1: Pristine...

Triangulations and bracketings This is a sequence challenge. So you will output a sequence per default rules. I will give two different interpretations of what this sequence means. The two both give the sequence so feel free to follow whichever one you feel. As an extra challenge figure out why t...

Terminal Paint Note: This is my first attempt at writing a challenge. I thought that it was a good idea, but the complexity of it became overwhelming. Please tell me if you see any mistake or if you have any question concerning this challenge. code-golfascii-artgrid Write a full program that can ...

Interpret a SqueezeL string SqueezeL is a golfing language I'm developing. Its main distinguishing feature is its 40 character code page, which led me to create a semi-complicated encoding method for string literals, which I think could be an interesting code golf challenge. Input Any string cons...

Introduction You are tasked with creating a function that takes a binary number as input and determines whether it meets specific criteria based on combinatorics. Challenge Check if the number of '1's in the binary representation is even or odd, and if the total number of bits is a prime number. ...

Objective Count the number of ways to choose k items from n distinct items. Input: Two integers, n (total items) and k (items to choose). Output: An integer representing the number of combinations. Functionality Overview: Use the formula for combinations: \$ C(n, k) = \frac{n!}{k!(n - k)!}\$...

Associative, alternative, flexible, oh my An operation \$(\ast)\$ is associative iff \begin{equation} x\ast(y\ast z) = (x \ast y) \ast z \end{equation} for any choice of \$x\$, \$y\$, and \$z\$. A lot of useful operations are associative. However sometimes an operation is almost associative, but ...

Free Kei Friday A kei (圭) is an algebraic structure that abstracts the idea of mirror reflections. The kei is given as a set of mirrors \$X\$ and a closed reflection operation \$(\rhd) : X\times X\rightarrow X\$. We say that \$a \rhd b\$ represents the reflection of \$a\$ in \$b\$. Reflections fo...

Print all rational optimal 13-square packing placements The proven optimal way to pack 13 squares into a larger square is this: You can create many variations of this by sliding the blocks around. All of them are optimal. Your task is to output all rational ones that don't involve rotation. Inpu...

Convert to Vib-Ribbon Introduction vib-ribbon is a rhythm game for the PlayStation. According to the Vib-Ribbon Wikia, Vib-Ribbon's scoring system is unique in that it does not use numbers, but shapes (sometimes called Score Coupons) that represent different amounts of points. The value of the c...

Where is it midnight? With the passing of ex-president Jimmy Carter, a meme twitter account titled "Did Jimmy Carter Die Today?" erroneously tweeted the usual "No": Somme commenters argued that the post should really have been made at midnight, ensuring complete data about the last day, but this...

When's my payday? Description I get paid on the 28th of each month, except where the 28th falls on a weekend (Saturday or Sunday). In that case, payday is the previous working day. For this challenge you can ignore national holidays, assume every Monday-Friday is a working day. Input and Output I...

GCD for small numbers (1<=x<=64) without using L1 cache. The goal is to compute the Greatest Common Divisor (GCD) of two small numbers ($1 ≤ x ≤ 64$) as quickly as possible without using the L1 cache. Constraints: You are not allowed to store the result in an array. You can memoize auxiliary tab...

The crossword game In this game, each player starts with an empty 5x5 grid. Players in turn say a letter of the alphabet, which all players must write in their grid, in any location. Once all the grids are filled (so, after 25 turns), each player totals their score and the highest score wins. Sco...

Pretty-print a table... but with ASCII Objective Given an ASCII string that encodes a table in the format defined below, pretty-print it using Unicode box-drawing characters. Input format The input format identifies the cells of the table using ASCII control characters, namely \v (vertical tab; 0...

Draw an ASCII "analog-digital" clock Write a function (or a whole program) that, given the hour and minute (in any reasonable format) outputs (or prints) the analog-digital corresponding clock. The canvases for the hour and minutes are as following, and you have to superimpose the two and print o...

Basic Uiua Planet Notation code-golf uiua Sandbox note: I have another challenge in the works which expands on this one and includes more complicated "planet notation" expressions. Uiua is a stack-based array programming language, and with the great power of a stack comes the great responsibility...

Is it protein? code-golf chemistry Given the molecular formula of a molecule, determine whether or not it could be a polypeptide in as few bytes of code as possible. Details A polypeptide is a polymer of amino acids, typically referring to a long chain, but here meaning any chain of one or more a...

id, di, pi, dp, dip code-golf uiua In the programming language Uiua, code is written with special Unicode symbols, called glyphs, rather than letters. For example, a program to display a Mandelbrot set might look like the following: (try it) ×2 ⊞ℂ⤙-1/4 -1/2÷⟜⇡300 >2 ⌵ ⊙◌⍥⊸(+×.) 50 0 Since most o...

Objective Given a date in the format YYYY-MM-DD, your task is to compute the factorial of the sum of the digits in the date. Input: A single line containing a date in the format YYYY-MM-DD. Output: The factorial of the sum of the digits in the date. Test Cases: Include a variety of valid dat...

Calculate Minecraft Fall Damage In the video game minecraft, the formula for the fall damage for player characters you get is often cited as MAX(0, CEIL(d-3)) [1]. Experimentally, this is not quite true because of intricacies of the calculation being done per game ticks (1/20th of a second). Your...

Get a random code golf question The purpose is simple: in your language of choice, get a random link of a question from the https://codegolf.stackexchange.com You can run something, make user click a button, etc. What matters is the output is a link of a question from the Code Golf site that has ...

Find a fraction's parent in the Stern-Brocot tree Objective Given a positive reduced fraction, output its parent in the Stern-Brocot tree. The outputted fraction shall also be reduced. The Stern-Brocot tree The Stern-Brocot tree is a infinite-height complete binary (search) tree that accommodates...

Bouba or Kiki popularity-contest decision-problem In Psychology, the Bouba/Kiki Effect refers to the non-arbitrary associations between sounds and shapes. The traditional example shapes are a spiky blob, an a rounded blob Source: Wikipedia CC BY-SA Humans seem to have an innate understanding of ...

How many 2x4s can you make from a log? code-golf geometry You have a pile of logs that you want to mill into two-by-four inch boards to build a new stand for your grilled-cheese sandwich business. You've counted and measured all the logs, but can you get all the lumber you need out of them? Chall...

RemiND me WHat MY PassWord Is Unfortunately, I've forgotten what my password is. I wrote it down somewhere, but, because I know it is bad security to just have passwords written down, I instead wrote it down in hints. In these hints, I wrote down two things about the casings of each letter in my ...

There are 10 prisoners in a prison. The prison has a central living room with one light bulb, which is initially switched off. Each day, the warden picks a prisoner at random and escorts him to the living room. The prisoner can either choose to turn the light bulb on or off, or do nothing, and th...

Count Leap Years in a Given Range Objective You are tasked with writing a function that counts the number of leap years between two given years, inclusive. A leap year is defined as follows: A year is a leap year if it is divisible by 4. However, if the year is divisible by 100, it is not a leap...

Find the nth occurrence of a character code-golf string Challenge Given a string s, a character c, and a number n, return the position of the nth occurrence of c in s. If c does not have an nth occurrence in s, you can return a number outside the range of the string, or another type of object ent...

Name the nth Tama successor Tama was a cat who gained fame for being a railway station master and operating officer at Kishi Station on the Kishigawa Line in Kinokawa, Wakayama Prefecture, Japan. Photo credit: User:Sanpei on Japanese Wikipedia, CC BY-SA 3.0 On her death, she was honored with a S...