Questions tagged [restricted-complexity]

Challenges with a spec which requires all answers to meet certain time complexity restrictions. This could be specific ("Your answer must be O(n^2) where n is the number of items in the input"), or at the level of complexity classes ("Your answer must be polynomial in the number of items in the input").

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22
votes
6answers
4k views

Chinese Remainder Theorem

The Chinese Remainder Theorem tells us that we can always find a number that produces any required remainders under different prime moduli. Your goal is to write code to output such a number in ...
5
votes
7answers
1k views

Return the first N primes

With a twist; your algorithm has to be less complex than O(X2) where X is the Nth prime. Your solution post should include the character count and the theoretical complexity in terms of X (or N, which ...
14
votes
1answer
368 views

Solve Subset-Sum in polynomial time (…if P = NP)

Shocking news: Dr. Mad J Scientist has released a proof of P = NP to the world. But the proof is nonconstructive, and she's keeping the algorithm to herself. Worry not. Without even looking at her ...
18
votes
20answers
3k views

Give a permutation with no two consecutive integers next to each other

Challenge Given an integer n ≥ 4, output a permutation of the integers [0, n-1] with the property that no two consecutive integers (integers with absolute difference 1) are next to each other. ...
46
votes
1answer
5k views

Longest common substring in linear time

This challenge is about writing code to solve the following problem. Given two strings A and B, your code should output the start and end indices of a substring of A with the following properties. ...
24
votes
2answers
960 views

Write an Incident tokeniser

Background Incident is a fairly unusual programming language, in that its list of tokens is not predetermined, but rather inferred from the input. As such, tokenising an Incident program can be ...
21
votes
2answers
1k views

Book Stack Sort

When stacking books you usually want to put the largest ones at the bottom and the smallest ones at the top. However, my latent OCD makes me feel very uneasy if I've got two books where one is shorter ...
20
votes
3answers
434 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, ...
13
votes
15answers
3k views

Pick the longest stick

You are a young programming geek living with your 2 other best friends. Every week, one of you has to do all the chores of the house and you decide whose turn it is by picking a stick. The one who ...
7
votes
0answers
768 views

Stable positive/negative separation [closed]

From SO. You are given an array with positive and negative integers. Write a function to change the elements order in the array such that negative integers are at the beginning, the positive integers ...
11
votes
9answers
1k views

A classic sorting code-golf question

This is a code-golf question. Input A list of non-negative integers in whatever format is the most convenient. Output The same list in sorted order in whatever format is the most convenient. ...
5
votes
13answers
869 views

Generate the list [1, 0, -1, 0, 1, 0, -1, 0, …] [closed]

In the spirit of a question on math.se: given an integer n, return the integer in position n of the sequence [1, 0, -1, 0, 1, 0, ...
7
votes
3answers
462 views

Convolve integers in subquadratic time

An linear discrete convolution is an operation that turns two vectors of numbers into a third vector of numbers by multiplying elements inside-out. Formally, for two vectors ...