# Questions tagged [open-ended-function]

For challenges where an exact output is not required but some property must still be fulfilled.

102 questions
Filter by
Sorted by
Tagged with
3k views

### Be big more often

Related You are a manager at a large number factory. You want to show everyone your business is doing well, by showing randomly chosen samples. Unfortunately, your business is not doing that well. But ...
1k views

### Encode the input to exclude a given character (part 1)

Your task is to write 2 functions/programs. They may share code. The first function must, given a string and a character, output a new string that does not contain that character. The second function ...
195 views

### Give the best Chaitin incompleteness bound

This was originally a pure mathematics question, but I think I've got the best chance for an answer here. The Challenge For concreteness, consider Peano Arithmetic (PA). For some language L of your ...
2k views

### Make a super fair number

An even distribution number is a number such that if you select any of it's digits at random the probability of it being any particular value (e.g. 0 or ...
5k views

### Turing-Complete Language Interpreter

A challenge I thought that would be very cool is to make an interpreter for a Turing-complete language of your choosing. The rules are simple: You may use any language to create this interpreter ...
583 views

### Output a Steiner quadruple system

A Steiner quadruple system $SQS(n)$ is a collection of subsets (blocks) of size 4 of a set $S$ of size $n$ such that every subset of $S$ of size 3 is in exactly one block. It is easy to show ...
398 views

### Convert numbers to dice patterns

The way points are assigned on a dice follows a regular pattern, the center dot is present if and only if the number is odd. To represent the even numbers, pairs of dots on opposite sides of the ...
3k views

### Transform characters of your choice into "Hello, world!"

Write a program or function that takes a character as input and outputs a character. Also, choose a list of 13 distinct ASCII printable characters (32-126). When a character from this list is passed ...
697 views

A followup to this challenge by Jeremy Collprav, inspired by DLosc solving this in Regenerate. Some sections copied from the linked challenge. Linking chains We define a chain to be a string ...
3k views

### Output a random unary string

Your task is simple: output the letter x a random number of times. Every possible length of xs must have a non-zero probability ...
3k views

### Give the fool's Fibonacci sequence

Recently I asked for tips on improving some code-golf of mine. The code was supposed to output every third value of the Fibonacci sequence starting with 2: ...
597 views

### Prefix code generator

In this challenge, we consider an encoding from positive integers (up to a limit) to binary sequences. Some examples: ...
10k views

### Print all integers

Write a program or function which will provably print all integers exactly once given infinite time and memory. Possible outputs could be: ...
612 views

### Generate a permutation from the high-water marks

Given a permutation, we can define its high-water marks as the indices in which its cumulative maximum increases, or, equivalently, indices with values bigger than all previous values. For example, ...
1k views

### Enumerate all pure sets

In set theory, a set is an unordered group of unique elements. A pure set is either the empty set $\{\}$ or a set containing only pure sets, like $\{\{\},\{\{\}\}\}$. Your challenge is to write a ...
1k views

Given a list, L, of sets of numbers like this: [, [0,2,3], [3,1], [1,2,3]] Output a single list of numbers such that 2 ...
3k views

### Sudoku as a SAT problem

Background An interesting way to solve a Sudoku puzzle is to represent it as a Boolean satisfiability problem, and then feed it to a SAT solver. A Boolean Satisfiability Problem (abbreviated as SAT ...
3k views

### Create an array with repeated numbers

Challenge Your task in this question is to write a program or a named function which takes a positive integer n (greater than 0) as input via STDIN, ARGV or ...
2k views

### Output every sublist ... eventually

You will be given as input an infinite stream of positive integers. Your task is to write a program which outputs an infinite sequence of lists with two requirements: All lists in the output are ...
8k views

### Print some JSON

This challenge is straightforward, but hopefully, there are plenty of avenues you can approach it: You need to print/return a valid JSON object of at least 15 characters, not counting unessential ...
2k views

### Enumerate the rationals

The cardinality of the set $\mathbb Q$ of rational numbers is known to be exactly the same as that of the set $\mathbb Z$ of integers. This means that it is possible to construct a bijection ...
3k views

### Don't repeat yourself

In this challenge you will be tasked with implementing a sequence of natural numbers such that: Each number appears a natural number of times No two numbers appear the same number of times No two ...
333 views

### Busy beaver in a coin

$BB$ is the busy beaver function, an uncomputable function. Write a program which when given an integer $n$ as input, will output $BB(n)$, with at least $\frac 2 3$ probability. You can do ...
3k views

### Egyptian fraction representations of 1

An Egyptian fraction is a representation of a rational number using the sum of distinct unit fractions (a unit fraction is of the form $\frac 1 x$ where $x$ is a positive integer). For all ...
2k views

### Add two real numbers ... probably

The problem statement here is pretty simple, take two real numbers on the range [0,1) as input and output their sum, with probability 1. The catch here is that there are a lot of real numbers. There ...
355 views

### Injectively saturate bit strings

It can be easily proven using Hall's marriage theorem that given fixed $n$ and $k<n/2$, there is an injective (one-to-one) function from all $n$-bit strings with $k$ ones to $n$-bit ...
752 views

### Mapping Passing Through Point

(Inspired by this challenge.) Given six real values in three pairs: $(x_1, x_2), (y_1, y_2),$ and $(x_0, y_0)$, where $x_1 < x_0 < x_2$ and $y_1 < y_0 < y_2$, create a function ...
417 views

### Generate number from given range

Your function must accept three numbers in any order: A signed real number (or ±Infinity) - The number (N) for which you have ...
1k views

### Approximate a root of an odd degree polynomial

Every odd degree polynomial has at least one real root. However this root does not have to be a rational number so your task is to output a sequence of rational numbers that approximates it. Rules ...
1k views

### Code Golf: Mix the nuts so that none of the same kind are touching

Input: Input is a randomized array of nuts (in your language), the possible nuts follow. Your program must have a way of representing each kind of nut, such as an integer code. Program must be able ...
5k views

### Infinitely many ℕ

Background: A sequence of infinite naturals is a sequence that contains every natural number infinitely many times. To clarify, every number must be printed multiple times! The Challenge: Output a ...
1k views

### Split some points

proposed by @Adám in chat Given an even number of finite points return a line $y=mx+b$ that evenly splits the points on both sides. Specs Take a list of distinct points $(x,y)$ (or a list of x-...
425 views

### Number-only switch

Write a function that takes an ASCII-printable-only (all charcodes ∈ [32..126]) string input x and provides an ASCII-printable-only output string ...
1k views

### Surjection from one string to two strings

This is the inverse of negative seven's question. Write a program or function which, given any single, possibly-empty string of printable ASCII (codes $[32,126]$) outputs or returns two strings of ...
3k views

### Give me odd, even, square, cube, prime and composite 3-digit numbers

Given a string which is guaranteed to be either odd, even, square, ...
2k views

### Generate an arbitrary half of a string

Given a string $x$, we say another string $y$ is half of it, if both of the following properties are true: $y$ is a (not necessarily continuous) subsequence of $x$ - there exists a ...
345 views

### Don't output the file 2

Last time you were required to write program that output a file, such that no byte is same as original file. The request meant to let everyone carry part of information, but it ends up that everyone ...