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# Questions tagged [decision-problem]

For challenges which involve deciding whether or not the input meets certain criteria, and outputting some data, representing that decision.

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15 votes
14 answers
2k views

### Wait, ASCII was 128 characters all along?

Challenge In this challenge, you have to take a nonnegative integer as input, convert it into base-128 bytes (0 → 0x00, 127 → ...
19 votes
28 answers
2k views

### Is it a tower permutation?

A tower is made out of layers, each one being one unit shorter than the one below it. Every layer is completely on top of the previous layer. For example, here is a tower along with it's height map: <...
18 votes
10 answers
1k views

### Is this a word?

Toki pona is a minimalist constructed language, and thus it has minimalist phonotactics (rules describing what sounds make valid words). Toki Pona has 8 consonant sounds ...
11 votes
6 answers
688 views

### A sorcerer's spellbook

Edit: I haven't played D&D before so when I initially made this question I didn't properly research it. I apologize for this, and I'm making a few edits that might invalidate answers to stay as ...
13 votes
8 answers
2k views

### Is Wally there?

Inpired by recent Stand-up Maths' video. Task Wrapping a list x can be seen as inserting "line-breaks" into x every <...
20 votes
15 answers
2k views

### Sorting with a deque

You're given an array of positive integers. Your job is to sort them using an initially empty deque (double-ended queue) by the following procedure: Take a number from the front of the array, and ...
11 votes
15 answers
2k views

### Is this a Hadamard matrix?

Hadamard matrices is a square matrix whose entries are either +1 or −1 and whose rows are mutually orthogonal. In other words, it means that each pair of rows has matching entries in exactly half of ...
24 votes
27 answers
3k views

### Is it a row of Pascal's triangle?

Pascal's triangle is a triangular diagram where the values of two numbers added together produce the one below them. This is the start of it: ...
9 votes
13 answers
1k views

### Is it an option for the ls utility specified in POSIX.1-2017?

The ls utility lists specified directory content. It is infamous for stupidly lots of options which is known for anti-pattern design of implementing software.(...
53 votes
100 answers
8k views

### Is it a pangram?

Write a function or program that takes as its input a string and prints a truthy value if the string is a pangram (a sequence of letters containing at least one of each letter in the English alphabet) ...
3 votes
1 answer
119 views

### Detect revokes in Jass

Jass is a trick-taking game for four players and the national card game of Switzerland. It is played with a 36-card deck, four suits each with ranks 6, 7, 8, 9, 10, J, Q, K, A. We will be using French ...
28 votes
4 answers
10k views

### ¿xu ti te gismytermorna? (Is it a valid gismu?)

(Literally: "Does this follow/realize the gismu-form?") Premise The language Lojban is a constructed language, meaning in part that all of its words have been created rather than allowed to develop ...
30 votes
63 answers
4k views

### Is it a pure word?

Introduction A pure word (or perfect word), as defined by me, is a word where the sum of the position in the alphabet of each letter in the word is perfectly divisible by the total length of the word. ...
18 votes
4 answers
418 views

### Are there mountain rings?

Challenge Given a matrix of positive integers, determine if there are any "rings" of mountains. The formal definition for this challenge is: given a matrix of positive integers, is there any positive ...
28 votes
12 answers
2k views

### Infinite ordinals from a well-ordering

Your task is to write a short program that represents a large (infinite) ordinal, using a well-ordering of the set of positive integers. Your program will take two different positive integers and ...
29 votes
69 answers
8k views

### Is string X a subsequence of string Y?

Given strings X and Y, determine whether X is a subsequence of Y. The empty string is regarded as a subsequence of every string. (E.g., '' and ...
22 votes
6 answers
588 views

### Modified Boggle Checker, with Modified Boggle-able Code

Background Boggle is a board game where the players have to find English words on a 4-by-4 board of random alphabets. Words can be constructed by selecting sequentially adjacent cells on the board. ("...
38 votes
41 answers
4k views

### Is my Matrix Arrowhead?

Definition An arrowhead matrix is a matrix that has all entries equal to 0, except the ones on the main diagonal, top row and leftmost column. In other words, the matrix should look like this: * * * *...
18 votes
26 answers
2k views

### Is it a tetrate of two?

The tetration operation consists of repeated exponentiation, and it is written ↑↑. For instance, 3↑↑3 =3 ^(3^3) = 3^27 = 7,625,597,484,987 A tetrate of two is an ...
16 votes
20 answers
3k views

### Doubleouble Talkalk

Input A non-empty string or list of capital letters k with length between 3 to 5000. Output A value indicating whether k can be ...
44 votes
17 answers
2k views

### No strings attached!

Intro There are 3 nails in the wall. You've got a piece of string that is fixed to the picture frame with both ends. To hang the picture, you entangled the string with the nails. But before letting ...
20 votes
23 answers
1k views

### Is this a valid PZN?

Is this a valid PZN? A Pharmazentralnummer, or PZN, is an eight-digit code which uniquely identifies medications, medical products, and similar items in the German healthcare system. Examples include ...
236 votes
369 answers
66k views

### Is this number a prime?

Believe it or not, we do not yet have a code golf challenge for a simple primality test. While it may not be the most interesting challenge, particularly for "usual" languages, it can be nontrivial in ...
15 votes
5 answers
1k views

### Is this a solvable Numberlink?

Challenge Per Wikipedia: Numberlink is a type of logic puzzle involving finding paths to connect numbers in a grid. The player has to pair up all the matching numbers on the grid with single ...
13 votes
3 answers
646 views

### Can this polyomino tile the toroidal grid?

Inspired by certain puzzles on Flow Free: Warps. Background We all know that L-triominos can't tile the 3x3 board, and P-pentominos can't tile the 5x5 board. But the situation changes if we allow the ...
26 votes
9 answers
3k views

### Is it a Valid Crossword Grid?

In crossword terminology, the grid is the region into which the crossword answers are inserted, consisting of white and black squares. The crossword answers, called entries, are inserted into ...
16 votes
4 answers
572 views

### Does the fishy road have an end?

I love ><>, ><> is life! 2D langages are amazing! In this challenge, you will have to say if a "fishy" road has an end, while code-golfing. Definition A fishy road is constructed with tiles, ...
40 votes
41 answers
5k views

### Is there a bump?

Given a list of positive integers determine if there is an element that is either greater than its two neighbors or less than its two neighbors (a "bump"). To be clear a bump can never be the first ...
29 votes
13 answers
3k views

### Word Search Puzzle

Given a rectangular text as a word search puzzle and a search string, determine if the text contains the search string. The search string may appear: horizontally, vertically or diagonally forwards ...
22 votes
24 answers
3k views

### Is it true? Ask Pip!

Title is an homage to this classic challenge In Pip, the Scalar data type encompasses strings and numbers. A Scalar value is truthy in most cases. It is falsey only if: It is the empty string ...
57 votes
136 answers
19k views

### Is this number evil?

Introduction In number theory, a number is considered evil if there are an even number of 1's in its binary representation. In today's challenge, you will be identifying whether or not a given number ...
43 votes
116 answers
6k views

### Divisibility test

Task Given two strictly positive integers n and d as input, determine whether n is evenly divisible by d, i.e., if there exists an integer q such that n = qd. You ...
36 votes
41 answers
4k views

### Is it a Mersenne Prime?

A number is a Mersenne Prime if it is both prime and can be written in the form 2n-1, where n is a positive integer. Your task is to, given any positive integer, determine whether or not it is a ...
29 votes
37 answers
2k views

### Where are Champernowne's zeroes?

Consider the infinite string of all nonnegative decimal integers concatenated together in order (akin to Champernowne's constant): ...
21 votes
4 answers
2k views

### Crossing a river with weird animals

Background One kind of river-crossing problems involves two kinds of animals. One such problem reads like this: (all wordings, including animal species, are arbitrary) A farmer has to cross a river ...
25 votes
14 answers
2k views

29 votes
5 answers
2k views

### Can I Clear The Grid?

I recently found this game and have been enjoying it. Basically, there is a grid of colored tiles and you act by clicking on empty spaces. When you click an empty space, the first tile (if any) in ...