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Questions tagged [open-ended-function]

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

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10 votes
4 answers
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Output a 1-2-3-5-7... sequence

Follow-up of my previous challenge, inspired by @emanresu A's question, and proven possible by @att (Mathematica solution linked) For the purposes of this challenge, a 1-2-3-5-7... sequence is an ...
Tbw's user avatar
  • 2,083
21 votes
15 answers
2k views

Output a 1-2-3 sequence

For the purposes of this challenge, a 1-2-3 sequence is an infinite sequence of increasing positive integers such that for any positive integer \$n\$, exactly one of \$n, 2n,\$ and \$3n\$ appears in ...
Tbw's user avatar
  • 2,083
12 votes
7 answers
1k views

Horsey sightseeing

A knight's tour is a sequence of moves of a knight on a chessboard such that the knight visits every square only once. For those who are not aware of how knights in chess work, knights are capable of ...
totallyhuman's user avatar
  • 17.2k
19 votes
9 answers
981 views

Output an infinitely proportional sequence

In this challenge, an infinitely proportional sequence is defined as a infinite sequence of positive integers such that: All positive integers are contained infinitely many times within the sequence. ...
emanresu A's user avatar
  • 38.4k
17 votes
12 answers
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 ...
mousetail's user avatar
  • 12.6k
6 votes
0 answers
206 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 ...
Charles Wang's user avatar
9 votes
9 answers
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 ...
Wheat Wizard's user avatar
  • 98.8k
16 votes
3 answers
443 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 ...
bsoelch's user avatar
  • 6,015
18 votes
22 answers
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 ...
The Empty String Photographer's user avatar
16 votes
5 answers
703 views

Prefix code generator

In this challenge, we consider an encoding from positive integers (up to a limit) to binary sequences. Some examples: ...
Bubbler's user avatar
  • 76.7k
13 votes
9 answers
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: ...
Wheat Wizard's user avatar
  • 98.8k
13 votes
8 answers
710 views

Generate all linked chains

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 ...
caird coinheringaahin g's user avatar
14 votes
5 answers
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 ...
alephalpha's user avatar
  • 48.2k
13 votes
10 answers
1k views

Adjacent Items Sorting

Given a list, L, of sets of numbers like this: [[1], [0,2,3], [3,1], [1,2,3]] Output a single list of numbers such that 2 ...
mousetail's user avatar
  • 12.6k
24 votes
5 answers
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 ...
Wheat Wizard's user avatar
  • 98.8k
12 votes
7 answers
787 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 ...
97.100.97.109's user avatar
0 votes
6 answers
421 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 ...
EzioMercer's user avatar
  • 1,473
13 votes
14 answers
615 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, ...
Command Master's user avatar
8 votes
3 answers
365 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 ...
Parcly Taxel's user avatar
  • 3,737
12 votes
6 answers
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 ...
AndrovT's user avatar
  • 2,796
20 votes
9 answers
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-...
math scat's user avatar
  • 9,328
22 votes
17 answers
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 ...
Wheat Wizard's user avatar
  • 98.8k
8 votes
4 answers
427 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 ...
l4m2's user avatar
  • 24.4k
5 votes
2 answers
354 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 ...
l4m2's user avatar
  • 24.4k
19 votes
10 answers
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 ...
att's user avatar
  • 20.6k
4 votes
1 answer
187 views

Show a balanced binary tree

Given an integer \$n > 1\$, output a balanced binary tree with \$n\$ leaf nodes. The tree should be constructed out of (space), ...
97.100.97.109's user avatar
7 votes
9 answers
329 views

Incomparable partitions

A partition of a list \$A\$ is a way of splitting \$A\$ up into smaller parts, concretely it is list of lists that when concatenated gives back \$A\$. For example ...
Wheat Wizard's user avatar
  • 98.8k
21 votes
11 answers
2k views

Create a nibble shorthand

I recently stumbled across this image on wikimedia commons. It's a little bit of an information overload at first, but after examining it a bit it shows an interesting number system for writing ...
Wheat Wizard's user avatar
  • 98.8k
29 votes
20 answers
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 ...
Jiří's user avatar
  • 1,885
7 votes
5 answers
339 views

Generate number set with conditions using n numbers

Generate \$T=\{T_1,...,T_x\}\$, the minimum number of \$k\$-length subsets of \$\{1,...,n\}\$ such that every \$v\$-length subset of \$\{1,...,n\}\$ is a subset of some set in \$T\$ Here, \$n > k &...
2FaceMan's user avatar
  • 179
22 votes
24 answers
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 ...
Command Master's user avatar
2 votes
0 answers
47 views

Bijective Function (mapping integer to arbitrarily large integer tuple) [duplicate]

Find a bijective function which maps integers to arbitrarily large tuples of integers. Given the input \$n\$, output the tuple it matches to. Edit: The empty tuple is included in the mapping.
dancxviii's user avatar
  • 193
17 votes
15 answers
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 ...
emanresu A's user avatar
  • 38.4k
20 votes
25 answers
3k views

Give f and g that sometimes commute

Let \$Z\$ be either the integers, the positive integers, or the non-zero integers; pick whatever's convenient. Give two functions \$f\$ and \$g\$, each \$Z \to Z\$, such that: \$f(g(a)) = g(f(a))\$, ...
cjquines's user avatar
  • 1,231
16 votes
15 answers
1k views

Average-ignorant sets of integers

Recently a friend of mine posed the following: What subset of the integers satisfies the condition if distinct a and b are in the subset, their average is not in the subset? I know the set of non-0 ...
Binary198's user avatar
  • 515
14 votes
3 answers
866 views

Sniff out biased random permutations

The brilliant engineers at <enter company you love to hate> have struck again. This time they've "revolutionised" the generation of random permutations. "Every great invention is ...
loopy walt's user avatar
  • 16.7k
17 votes
9 answers
2k views

Is it irrational?

Your task is to make a program that decides if a real number between 0 and 1 is irrational or not. As stated, this is obviously impossible, so instead we will use the following definition: ...
AnttiP's user avatar
  • 7,898
15 votes
3 answers
370 views

What was my Wordle play?

Task Given a winning Wordle play results (clues), the target ("secret") word and a list of words, output a possible sequence of words leading to such results. The words in the list will be ...
pajonk's user avatar
  • 16.2k
38 votes
58 answers
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 ...
pxeger's user avatar
  • 23.7k
12 votes
8 answers
842 views

All sequences as substrings

Make a program that outputs a sequence of integers so that every finite sequence of positive integers is a substring (continuous subsequence) of the output. For example, the following sequence ...
AnttiP's user avatar
  • 7,898
15 votes
4 answers
601 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 ...
Parcly Taxel's user avatar
  • 3,737
4 votes
7 answers
750 views

Don't output the file

This rar file, when decompressed, gives a 65024-byte exe file. Requiring you to output the contents of that file would be ...
l4m2's user avatar
  • 24.4k
16 votes
4 answers
602 views

Probability breaking sequences

If we have a finite list of elements we can determine the probability of any one element being drawn at random as the number of times it occurs divided by the total number of elements in the list. For ...
Wheat Wizard's user avatar
  • 98.8k
10 votes
8 answers
612 views

Biggest katlani noun dictionary in 400 bytes

Katlani is a constructed language being designed in chat. In this challenge, your goal is to print the largest dictionary of katlani nouns possible in 400 bytes or less. Task In 400 bytes or less, ...
Rydwolf Programs's user avatar
14 votes
8 answers
707 views

Compress and decompress

Your task is to make a bidirectional compressor. It takes a list of bytes as input and returns a list of bytes as output. It has the property than whenever it is iterated twice it returns the original ...
AnttiP's user avatar
  • 7,898
37 votes
20 answers
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[1] ...
pxeger's user avatar
  • 23.7k
7 votes
1 answer
344 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 ...
l4m2's user avatar
  • 24.4k
21 votes
13 answers
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 ...
Wheat Wizard's user avatar
  • 98.8k
18 votes
8 answers
872 views

Make every fixed list

We are to define the idea of a fixed list as follows: A fixed list is a list of fixed lists. This definition is recursive so it's useful to look at some examples. The empty list ...
Wheat Wizard's user avatar
  • 98.8k
18 votes
20 answers
1k views

Generate a regular graph

Inspired by this Mathematica.SE post Given two positive integers \$n, k\$ with \$n > k \ge 1\$, output a binary \$n\times n\$ matrix such that every row and column contains exactly \$k\$ 1s, and ...
caird coinheringaahin g's user avatar