Questions tagged [decision-problem]
For challenges which involve deciding whether or not the input meets certain criteria, and outputting some data, representing that decision.
802 questions
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Directory traversal attack detection
Given a path to a file or a directory, detect whether the path can traverse to outside the current working directory, or attempt to traverse to the "parent directory" of the root directory.
...
- 805
18
votes
24
answers
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Is there an even distance pair?
In this challenge you will receive a list of integers as input. Your program should then determine if there are two equal values in the list at an even distance from each other.
This is code-golf so ...
- 104k
242
votes
384
answers
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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 ...
- 212k
19
votes
9
answers
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Is the union of these rectangles a rectangle?
The intersection of two rectangles is always a rectangle (if you consider the empty set to be a rectangle). But the union of two rectangles is not necessarily a rectangle.
Given two rectangles as ...
- 104k
14
votes
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Identify Redundant Regex
A redundant regular expression (regex) is defined here as a regex which has some amount of characters which can be removed while not affecting its functionality -- i.e. it matches the exact same set ...
- 7,505
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Does your source code contain this character?
Given a character as input, determine if your source code contains that character or not.
Shortest code wins. Though, I'd like to see some "normal" languages too.
UPDATE: the question ...
- 383
83
votes
273
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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), ...
- 5,435
15
votes
17
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IMO 2025: Divisor sums that go forever
Problem 4 of the 2025 International Mathematical Olympiad asked (paraphrased):
Let \$f(n)\$ be the sum of the largest three proper divisors of \$n\$,
that is divisors excluding \$n\$ itself. For ...
- 150k
23
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Write two very different programs with the same characters
Your task is to write two programs/functions, in the same language.
Program 1: Verify that two inputs are anagrams of each other.
Program 2: Verify that two inputs differ from each other at every ...
- 8,130
30
votes
53
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Cubic Concatenation
Challenge
Given three non-negative integers \$a, b\$ and \$c\$, decide if the sum of their cubes is equal to the concatenation of those numbers, aka:
$$
a^{3}+b^{3}+c^{3} = a^\frown b ^\frown c
$$
...
- 559
13
votes
18
answers
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Is it a product of 4 unique primes (A046386)?
A046386 is the sequence of all natural numbers that are the product of exactly 4 distinct primes.
Write the shortest program, function, or code snippet, that, when given a natural number, outputs ...
- 11.5k
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votes
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iHateOddNumbers
Task
Given a non-negative number, check if it's odd or even. In case it's even, output that number. Otherwise, throw any exception/error that your language supports, and stop the program.
Example with ...
- 513
59
votes
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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 ...
- 1,692
7
votes
23
answers
998
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Can we escape from array?
Can we escape from the array?
Input: A non-empty array of non-negative integers (without nesting1).
Output: A boolean value2 indicating whether we can reach the end of the array when starting from the ...
- 424
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votes
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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 ...
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