# 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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### Is it an ordinal?

Background (feel free to skip) Ordinals are the abstract representation of well-orders. A well-order of a set is a total order, which basically means that every element in the set can be compared ...
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### Pairs at every distance

Given a list $X$ of 2 or more integers, output whether, for all $n$ such that $0 \leq n < length(X)-2$, there exists a pair of equal integers in $X$ separated by exactly $n$ elements. In ...
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### Is it shuffled FizzBuzz?

A twin of this. FizzBuzz is where a range of positive integers is taken, and numbers divisible by 3 are replaced with "Fizz", divisible by 5 with "Buzz" and divisible by 15 with &...
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### Is this a strange pond?

In this challenge we considered a frog hopping around a lily pond. To recap the lily pond was represented as a finite list of positive integers. The frog can only jump forward or backwards by a ...
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### Check a mushroom forest

In this challenge you will receive a list of pairs of non-negative integers representing a mushroom forest. Each pair represents a mushroom whose center is at that horizontal coordinate. The only ...
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### Is it a heapable sequence?

A binary max heap is a rooted tree with integer labeled nodes such that: No node has more than 2 children. The label of every node is greater than all of its children. We say a sequence of integers ...
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### Is it a valid list?

Given a string like [[[],[[]]],[]], made of only commas and square brackets, your challenge is to determine whether it represents a list. A list is either: ...
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### Can the 🐸 visit all the 🪷?

In this challenge you will be simulating a frog jumping from lily-pad to lily-pad in a pond. A frog's jump distance is uniquely determined by the size of the lily pad it jumps from. So for example ...
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### Detect Mongolian vowel harmony

The Mongolian language has "vowel harmony". In short the vowel harmony means that certain vowels are not allowed to be placed next to each other in a word. This means that suffixes of ...
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### lol is an ambigram, dad isn't

Given a word, decide if it is an ambigram. When rotated: b > q d > p l > l n > u o > o p > d q > b s > s u > n x > x z > z Assume ...
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### But is it a pretty place?

Your challenge, should you choose to accept it, is to take as input: A program in DirectionLang (as an ASCII string consisting of DirectionLang instructions) A list of pairs of integers, henceforth ...
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214 views

### Find run ascending lists faster

In this question I asked you to determine if a run ascending list could be made. It was code-golf so naturally most the answers are very slow. But what if we want it to be fast. In this challenge I ...
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### Can a run ascending list be made?

A run ascending list is a list such that runs of consecutive equal elements are strictly increasing in length. For example [1,1,2,2,1,1,1] can be split into three ...
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### Crossing a Lily Pond

The Narrative You are a frog who is at the edge of a pond with waterlilies. You would like to cross the pond without getting wet, so you plan to jump from lily to lily. There is, however, one problem: ...
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### 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 <...
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### Is this expression Python 2/3 safe?

Given an expression like 4 / 2 + 3, determine whether the expression has the same value in Python 2 and Python 3. Recall that in Python 2 division rounds down (so ...
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### Is this polynomial a square?

Given an integral polynomial $p$, determine if $p$ is a square of another integral polynomial. An integral polynomial is a polynomial with only integers as coefficients. For example, $x^2+2x+1$ ...
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### Is it 1089-able?

$1089$ is a very special number. To prove why, select any 3-digit number whose first and last digits differ by at least 2. Then, reverse the digits, and take the difference of these two numbers. ...
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### Will this makina program halt?

makina is a cell-based esolang composed of automata which move around a grid. These automata follow paths of instructions that direct their movement. Your task is to, given a makina program using only ...
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883 views

### Ragged list pattern matching

Given a pattern and a ragged list of positive integers, your task is to decide whether the pattern matches the ragged list. The pattern is also represented by a ragged list. But in addition to ...
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### Is this propositional formula an instance of an axiom?

Please help me automate my discrete mathematics homework. Given a valid propositional formula, check if it is an instance of one of Łukasiewicz's axioms. Here's how it works. A term can be defined ...
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### 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: ...
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### Can you draw this in one stroke?

Related | Related Given an ASCII art with |, _, and , check if you can draw the art in one ...
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### Can the Tune be Played?

Can the Tune be Played? Explanation A broken musical keyboard has keys labelled with positive integers. It is broken in two ways: It takes a long time to process key presses: after pressing the key ...
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### Gambling with an Alien

You met a 4-th dimensional being who challenged you to a game of dice. The rules are simple: each player rolls 3 6-sided dice and takes the sum of each combination of 2 dice. The player with the ...
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### Solve an alien wordle

You've arrived on an alien planet. The writing system, the culture and the language there are completely foreign to any language you know. But somehow they are all playing wordle already. So as a ...
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598 views

### Is it a sub-permutation?

A finite-permutation is a function which takes an $n$-tuple and produces an $n$-tuple such that every element of the input is present in the output, and the ordering does not rely on the values of ...
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### 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: <...
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### Is it a fibonacci-like sequence?

The Fibonacci Sequence is a sequence of positive integers where the first two elements are 1 and the rest are the sum of the previous two. It begins $1, 1, 2, 3, 5, 8, 13$ and continues forever. But ...
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807 views

### Golf the prime numbers in Shue

I'd like to introduce a new? programming language I call Shue (Simplified Thue). It has very simple syntax. Here is a program that checks if an input is divisible by three: ...
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### Is it a bigger regex?

You are given two regexes and your task is to determine if the strings matched by the first regex are a subset of the strings matched by the second regex. For this we are going to use a limited ...
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### Is given number a concat of two squares

Given a positive integer, determine if it can be represented as a concatenation of two square numbers. Concatenated numbers may not begin with 0 (except for 0). Any leading zeros in input should be ...
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### Mahjong Checker

Mahjong is a tabletop game played using tiles. It features three "number" suits (pins, sous, mans, represented as p, s ...
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### Can I wall glitch to there?

Background In a 2d game that I play, each screen is a 2d grid of tiles with walls and walkable tiles, with the player only able to travel on walkable tiles, and being stopped by walls. When the player ...
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### Write a spam-detection program

You work for a social media platform, and are told to create a program in a language of your choice that will automatically flag certain post titles as "spam". Your program must take the ...
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### Sum of two squares

Given a nonnegative integer $n$, determine whether $n$ can be expressed as the sum of two square numbers, that is $\exists a,b\in\mathbb Z$ such that $n=a^2+b^2$. ...
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### Check if a matrix is Zarankiewicz-maximal

My final-year project at the National University of Singapore is on Zarankiewicz's problem: What is the maximum number of 1s in an $m×n$ binary matrix ($m$ rows and $n$ columns) with no $a×b$ ...
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### Is it a possible Hearts result?

Hearts is a 4-player game that uses the following scoring rules: Everyone starts with score 0. Each round every player gets a non-negative amount of points. The sum of the points is 26, and at least ...
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### Reversed Multiple Pair

Intro Two numbers are a reversed multiple pair if they satisfy the following property: $$a\cdot b = \operatorname{reversed}( (a-1)\cdot b )$$ Here, $\operatorname{reversed}()$ means to reverse the ...
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### Is there a stable way to stack these?

If we have a binary matrix then we will say that a $1$ is stable if it is in the bottom row or it is directly adjacent to a $1$ which is stable. In other words there must be a path to the bottom ...
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836 views

### Is this hexagon symmetric?

TLDR: This is the hexagonal version of Is this square symmetrical? Given a hexagonal grid, decide if it is symmetric. The shape of the grid is a regular hexagon. Each cell in the grid has two possible ...
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### Predicting pumpkin planting plans' potential problems

You are going to be planting pumpkins soon, and you are preparing your supplies. Pumpkins come in all sorts of sizes and have their sizes written on the seed bag. A pumpkin that is size n will grow ...
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