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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8
votes
23answers
254 views

caN it be acrOnymised? [duplicate]

The Typical Way to Make an Acronym Out of a Phrase Is to Take the First Letter of Each Word: TTWMAOPITFLEW. howeveR, sometimEs, you can make an acronym of random ...
64
votes
197answers
19k views

Is this even or odd?

Note: There is not been a vanilla parity test challenge yet (There is a C/C++ one but that disallows the ability to use languages other than C/C++, and other non-vanilla ones are mostly closed too), ...
2
votes
20answers
467 views

Number in overlapping range

You are given two integers between lets say 1 and 12, one and two and a integer between lets say 0 and 4 which is called ...
44
votes
71answers
9k views

Is it double speak?

In an earlier challenge I asked code golfers to produce strings which copy each character in a string. For example: TThhiiss iiss ddoouubbllee ssppeeaakk!! ...
75
votes
84answers
10k views

Count of “a”s and “b”s must be equal. Did you get it computer?

In the popular (and essential) computer science book, An Introduction to Formal Languages and Automata by Peter Linz, the following formal language is frequently stated: mainly because this language ...
19
votes
10answers
2k views

Connect Four Validator

Introduction Connect Four is a game where you attempt to get four in a row: horizontally, vertically, or diagonally. In this code golf, we will be trying to find who won, given a game board. There ...
8
votes
16answers
2k views

Check if 2 arrays contain the same element

Write a program which will take for input 2 integer arrays and return a truthy value if there exists an element which is present in both of arrays, or a falsy one otherwise. The obvious solution to ...
41
votes
68answers
6k views

Is it a leap year?

This challenge is quite simple. You will take an input which will be a year from 1801 to 2400, and output if it is a leap year or not. Your input will have no newlines or trailing spaces: ...
31
votes
32answers
6k views

Is this n-speak?

Inspired by Is it double speak?, I devised a harder challenge. Given a string, determine if the string is n-speak, for any \$n\geq 2\$. N-speak is defined by repeating each letter \$n\$ times. With \$...
19
votes
3answers
405 views

One goes up, the other comes down

Introduction In this challenge, your task is to decide whether a given sequence of numbers can be separated into two subsequences, one of which is increasing, and the other decreasing. As an example, ...
34
votes
43answers
4k views

Yahtzee Small Straight Detection

In the game Yahtzee, players roll five six-sided dice, and attempt to create certain hands to score points. One such hand is a small straight: four consecutive numbers, not necessarily in order. The ...
8
votes
1answer
211 views

Radioactive Bit Checking

Note: This is the radiation-hardening version of my previous challenge Pristine Bit Checking. This should be much more difficult than that one. Write a program/function that takes two integers in the ...
28
votes
14answers
3k views

Pristine Bit Checking

Write a program/function that takes two integers in the range \$0\$ to \$255\$ inclusive, and returns whether the binary forms of the numbers are exactly one bit different. For example, \$1\$ and \$...
7
votes
6answers
774 views

Determine Beckett Grading Service (BGS) Final Grade

Introduction: Beckett Grading Service (aka BGS), is a company which encapusulates and grades Trading Card Game (TCG) cards (i.e. sport cards, Magic The Gathering, Pokémon, Yu-Gi-Oh, etc. etc.). The ...
16
votes
10answers
4k views

Write The Shortest Program To Check If A Binary Tree Is Balanced

For each node in a balanced binary tree, the maximum difference in the heights of the left child subtree and the right child subtree are at most 1. The height of a binary tree is the distance from ...
25
votes
55answers
6k views

Integer Lists of Noah

Introduction: I think we've all heard of it, but here a very brief summary: Noah gathered two of every species of animal on the planet, male and female, to save in his Ark during a great flood. The ...
38
votes
76answers
6k views

Is this number a factorial?

The Task Given a natural number as input, your task is to output a truthy or falsey value based on whether the input is a factorial of any natural number. You can assume that the input number will ...
21
votes
14answers
2k views

Is this a BST pre-order traversal?

Background A binary tree is a rooted tree whose every node has at most two children. A labelled binary tree is a binary tree whose every node is labelled with a positive integer; moreover, all ...
65
votes
46answers
7k views

Is it a Cyclops number? “Nobody” knows!

Task: Given an integer input, figure out whether or not it is a Cyclops Number. What is a Cyclops number, you may ask? Well, it's a number whose binary representation only has one ...
33
votes
77answers
4k views

Is this number a repdigit?

Challenge A repdigit is a non-negative integer whose digits are all equal. Create a function or complete program that takes a single integer as input and outputs a truthy value if the input number ...
24
votes
28answers
2k views

Magnanimous numbers

Given an positive integer as input determine if it is a magnanimous number. A magnanimous number is a number such that any insertion of a + sign between any two ...
17
votes
19answers
3k views

Hermitian matrix?

Note that this challenge requires no handling or understanding of complex numbers. Given a non-empty square matrix where every element is a two-element (Re,Im) integer list, determine (giving any ...
11
votes
5answers
777 views

Does this addition pyramid puzzle have a unique solution?

Given an addition pyramid \$P\$, determine whether it can be solved. An addition pyramid consists of layers, each having one number less than the one below it. Layer \$i\$ is symbolized as \$P_i\$. \$...
29
votes
21answers
1k views

Stackable sequences

You deal cards labeled 0 to 9 from a deck one a time, forming stacks that start at 0 and count up by 1. When you deal a 0, you place it on the table to start a new stack. When you deal any other ...
63
votes
82answers
11k views

Golf all the 16 logic gates with 2 inputs and 1 output!

For example, the gate A and B is a logic gate with 2 inputs and 1 output. There are exactly 16 of them, because: each logic gate takes two inputs, which can be ...
192
votes
287answers
44k 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 ...
37
votes
30answers
13k views

Wait, what language is this?

Recently I had the pleasure of writing a Haskell program that could detect if the NegativeLiterals extension was engaged. I came up with the following: ...
9
votes
16answers
1k views

MQTT subscription topic match

Background MQTT (Message Queuing Telemetry Transport) is an ISO standard publish-subscribe-based messaging protocol (Wikipedia). Each message has a topic, such as the following examples: ...
30
votes
31answers
5k views

Am I a Self Number?

A self number (also called a Colombian or Devlali number) is a natural number, x, where the equation ...
46
votes
139answers
12k views

Will it halt? (Robbers)

This is the robbers' thread. The cops' thread is here. Your challenge is to crack a cop's submission by finding an input that makes it halt. You don't have to find out why, or all inputs that make it ...
14
votes
15answers
1k views

Am I a Pillai prime?

A Pillai prime is a prime number \$p\$ for which there exists some positive \$m\$ such that \$(m! + 1) \equiv 0 \:(\text{mod } p)\$ and \$p \not\equiv 1\:(\text{mod }m)\$. In other words, an ...
8
votes
1answer
183 views

Compute my Sacred Geometry [closed]

In the tabletop RPG named Pathfinder, there is a feat that characters can take called Sacred Geometry, which allows a character who has it to buff their spells in exchange for doing some math: to use ...
5
votes
2answers
405 views

Can the cursor reach the bottom?

In a matrix of characters, a cursor is a movable position between two adjacent characters, before the first character or after the last character in a line, like that "I"-shaped indicator which moves ...
10
votes
3answers
830 views

Multi-user CRUD: Valid, Problem, or Error?

Introduction: Ever used Dropbox with some other people and you both modified the same file? Ever had a multi-user application with a relational database, and two people were modifying (or worse, one ...
-5
votes
5answers
108 views

Report divisibility with arithmetic integer operations only [closed]

Given two numbers, the first is greater than the second, check whether the first number is divisible by the second without a remainder. If divisible, answer "yes"(...
67
votes
47answers
9k views

Magic the Gathering: Friends or Foes?

In the card game Magic: the Gathering there are five different colours, which represent loose affiliations of cards, White (W), Blue (...
27
votes
21answers
1k views

Primenary Strings

A Primenary (binary-prime) string is one which, when written as a binary grid, every row and column has a prime total. That's quite a vague explanation, so let's break it down with a worked example.....
4
votes
14answers
957 views

Write the shortest code to match a tail-repeating string where one character falls off the head in each repetition

In this code-golf, you will attempt to match a string that is tail-repeating with one character falling off the head on each iteration. The code needs to be able to accept a string, and return to the ...
27
votes
12answers
1k views

Letter Boxed validator

The New York Times has a daily online game called Letter Boxed (the link is behind a paywall; the game is also described here), presented on a square as follows: You are given 4 groups of 3 letters (...
16
votes
13answers
3k views

Is my Rep in Stack-Exchange Form?

Premise: Your reputation is in Stack-Exchange Form if it can be represented by decomposing your medal counts (gold, silver, and bronze counted separately) into their base-10 digits and joining them ...
37
votes
53answers
6k views

Check whether letters of word are in alphabetical order

Write a function/program that accepts a string of lower/uppercase letters [A-Za-z] as input, that checks whether the occuring letters are unique and in alphabetical order (ignoring lower and uppercase)...
23
votes
17answers
3k views

Who won a Game of Bar Dice?

Challenge Bar Dice is a simple game played in a Bar with Dice (hence the name). You roll 5 six-sided dice and attempt to make the best hand. Scoring is based on amassing the largest number of ...
26
votes
81answers
4k views

Is it a whole number?

A number is whole if it is a non-negative integer with no decimal part. So 0 and 8 and ...
13
votes
9answers
402 views

Word Changer Reachability

Word changer is a game where you are trying to turn one word into another via single-character edits, with each step being its own word. For this challenge, edits may be replacements, insertions, or ...
24
votes
40answers
4k views

Check if a string is entirely made of the same substring

This is taken from this question (with permission ofcourse). I'll quote: Create a function which takes a string, and it should return true or false based on whether the input consists of only a ...
53
votes
33answers
4k views

Write the shortest self-identifying program (a quine variant)

Write a program that will generate a "true" output iff the input matches the source code of the program, and which generates a "false" output iff the input does not match the source code of the ...
17
votes
16answers
2k views

Do I have a twin with permutated remainders?

We define \$R_n\$ as the list of remainders of the Euclidean division of \$n\$ by \$2\$, \$3\$, \$5\$ and \$7\$. Given an integer \$n\ge0\$, you have to figure out if there exists an integer \$0<k&...
37
votes
27answers
3k views

Folding Numbers

Given a number determine if it is a folding number. A folding number is a number such that if you take it binary representation and "fold" it in half, That is take the result of XNOR multiplication ...
8
votes
25answers
795 views

Are the numbers amicable?

Two numbers are considered amicable if the proper divisor sum of the first is the same as the second number, the second number's proper divisor sum is equal to the first number, and the first and ...
21
votes
7answers
985 views

Is this a submatrix?

This is the 2-dimensional generalisation of this challenge. For our purposes, one matrix (or 2D array) A is considered a submatrix of another matrix B, if A can be obtained by completely removing a ...