Questions tagged [fastest-code]

The winner of a fastest-code challenge is determined by the runtime performance of the submissions. For fairness, all submissions should be benchmarked on the same machine, which usually means all submissions have to be tested by the host of the challenge. For scoring by asymptotic time complexity, use [fastest-algorithm] instead.

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14
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0answers
360 views

Find the number of n-by-n (-1, 0, 1) matrices with zero permanent as quickly as possible

The permanent of an \$n\$-by-\$n\$ matrix \$A = (a_{i,j})\$ is defined as: $$\operatorname{perm}(A)=\sum_{\sigma\in S_n}\prod_{i=1}^n a_{i,\sigma(i)}$$ For a fixed \$n\$, consider the \$n\$-by-\$n\$ ...
-2
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1answer
123 views

Symbol Search Deleter [rephrased] [closed]

Your challenge is to parse nonsensical text and output a "congruous phrase" - which I shall define here to be text with any contiguous characters in between, and including, a given set of like symbols ...
-5
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2answers
222 views

Fastest N times Hello World (Java/C/ C++) [closed]

Not a new one: Input N, being n, 0 ≤ n ≤ 5. Output N times "Hello World." Example: Input 3 Output Hello World. Hello World. Hello World. These 2 are my ...
8
votes
1answer
587 views

Compute OEIS A161169, approximately and quickly

\$T(n, k)\$ gives the number of permutations of length \$n\$ with up to \$k\$ inversions. This values grows very quickly, for example for \$T(20, 100) = 1551417550117463564\$. The maximum number of ...
3
votes
1answer
312 views

Find minimal set of rows to retain all unique values in each column

Given a matrix, the goal is to ensure all the values in each column occur at least once, while at the same time doing so requiring the least possible amount of rows. Fastest solution wins. Note: a ...
21
votes
8answers
2k views

The fastest Sudoku solver

Winner found It seems as if we have a winner! Unless anyone plans on contesting the world's current fastest Sudoku solver, user 53x15 wins with the staggeringly fast solver Tdoku. For anyone still ...
17
votes
9answers
1k views

Bentley's coding challenge: k most frequent words

This is perhaps one of the classical coding challenges that got some resonance in 1986, when columnist Jon Bentley asked Donald Knuth to write a program that would find k most frequent words in a file....
3
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1answer
281 views

Multiplication in Brainfuck - minimum number of evaluations [closed]

Given two numbers in tape location #0 and tape location #1 in Brainfuck, compute their product into another tape location (specify with answer). Optimize for the least amount of time-units used, where ...
5
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0answers
180 views

Fastest way to iterate over sublattice of discrete lattice

I need to construct a functor that iterates over the linear representation of a sub-lattice of size \$d_x,d_y,d_z,d_q\$ embedded in a lattice of size \$n_x,n_y,n_z,n_q\$. The sub-lattice corner is ...
6
votes
2answers
634 views

Check if all vowels exist in pairs of strings [closed]

Your program should find the number of string pairs (pairs of 2) that contain all vowels (a e i o u), when given an integer N and ...
25
votes
6answers
1k views

Prime containment numbers (speed edition)

This is sequence A054261 The \$n\$th prime containment number is the lowest number which contains the first \$n\$ prime numbers as substrings. For example, the number \$235\$ is the lowest number ...
10
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3answers
446 views

Arbitrary Randomness (Speed edition)

Given integer n, calculate a set of n random unique integers in range 1..n^2 (inclusive) ...
5
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2answers
299 views

Find arrays with distinct subarray sums

Consider an array A of length n. The array contains only integers in the range 1 to ...
9
votes
1answer
825 views

Count arrays that are really unique

This is a follow up to Count arrays that make unique sets . The significant difference is the definition of uniqueness. Consider an array A of length ...
0
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5answers
481 views

Fastest algorithm to output array containing all integers in range excluding duplicate digits

Input is a single integer in ascending digit order. The only valid inputs are: 12 123 1234 ...
11
votes
3answers
478 views

Count arrays that make unique sets

This question has a similar set up to Find an array that fits a set of sums although is quite different in its goals. Consider an array A of length ...
11
votes
2answers
574 views

Block partition a string

Inspiration. Consider a list l, consisting of numbers. Define a block operation at index i on the list ...
26
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2answers
1k views

Delete some bits and count

Consider all 2^n different binary strings of length n and assume n > 2. You are allowed ...
16
votes
1answer
325 views

Permutations such that no k+2 points fall on any polynomial of degree k

Description Let a permutation of the integers {1, 2, ..., n} be called minimally interpolable if no set of k+2 points (together ...
12
votes
8answers
2k views

Calculate the Hafnian as quickly as possible

The challenge is to write the fastest code possible for computing the Hafnian of a matrix. The Hafnian of a symmetric 2n-by-2n ...
9
votes
2answers
512 views

How many draws are there in Quarto?

Introduction This challenge is similar to Project Euler problems. I came up with it because I was playing a deceivingly simple board game and couldn't come up with an efficient solution to answer a ...
10
votes
2answers
528 views

Biggest square in a grid [closed]

Challenge Given a grid like this, ...
7
votes
3answers
829 views

The Missing Number - Version 2

Background: This question is a remix of the one that I made previously on this forum. The only difference with this one is: the range is significantly larger, AND dynamic. Details below! Also, I'm ...
22
votes
3answers
3k views

The Missing Number Revised

Background: I originally posted this question last night, and received backlash on its vagueness. I have since consulted many personnel concerning not only the wording of the problem, but also its ...
22
votes
9answers
1k views

Build an Electrical Grid

The Challenge There are N cities aligned in a straight line. The i-th city is located A[i] kilometers to the right of the origin. No two cities will be in the same ...
6
votes
3answers
355 views

Primitive roots density of number

Definition: A number m is called a primitive root of a prime p the condition that the smallest integer k for which p dividies mk-1 is p-1 Your task Given a tuple (a,b) of positive integers, ...
11
votes
7answers
942 views

Count arrays of periods

The period of a string is the shortest non-zero shift so that the string matches itself, ignoring any parts that overhang. So for example, ...
22
votes
8answers
1k views

Products that equal a sum and vice versa

A fun pair of equivalences is 1 + 5 = 2 · 3 and 1 · 5 = 2 + 3. There are many like these, another one is 1 + 1 + 8 = 1 · 2 · 5 and 1 · 1 · 8 = 1 + 2 + 5. In ...
3
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1answer
1k views

remove duplicates from array [closed]

You have given an array from which we need to remove duplicates. Rules: First or immediate duplicates gets removed first. Array contains natural numbers ...
17
votes
5answers
1k views

Fastest tweetable integer factorizer

The task is to find a non-trivial factor of a composite number. Write code that finds a non-trivial factor of a composite number as quickly as possible subject to your code being no more than 140 ...
20
votes
4answers
630 views

Plant trees in a park - As fast as you can!

This challenge is inspired by this app. The test cases are borrowed from that app. This is a fastest-code challenge, where the objective is to solve the largest test cases in the least amount of time....
2
votes
2answers
212 views

Tips for Fastest Code challenges [closed]

What general tips do you have for how to answer fastest-code challenges? Please post one tip per answer. The objective of these challenges is to make the program that will run in the least amount of ...
10
votes
2answers
451 views

Compute OEIS A005434

The task is to compute OEIS A005434 as quickly as possible. Consider a binary string S of length n. Indexing from ...
10
votes
1answer
555 views

Roll to see all sides!

Let's say you have a 20-sided die. You start rolling that die and have to roll it a few dozen times before you finally roll all 20 values. You wonder, how many rolls do I need before I get a 50% ...
14
votes
12answers
1k views

Finding approximate correlations

Consider a binary string S of length n. Indexing from 1, we can compute the Hamming ...
13
votes
4answers
381 views

Fastest Approximate Common Divisor

Overview In this challenge, you will be given two numbers which are both a small offset larger than a multiple of a medium-size number. You must output a medium-sized number that is almost a divisor ...
9
votes
5answers
1k views

Count the number of Hamming distance sequences

The Hamming distance between two strings of equal length is the number of positions at which the corresponding symbols are different. Let P be a binary string of ...
13
votes
2answers
972 views

Count how many distance sequences are far from all others

The Hamming distance between two strings of equal length is the number of positions at which the corresponding symbols are different. Let P be a binary string of ...
-5
votes
1answer
170 views

Google search result short summary [closed]

Intro When you search in google, it always shows you a result with a sample text from the found webpage. For example if you search for "Madonna greatest vinyl", google will show you one line link, ...
1
vote
0answers
280 views

Generalization of Eight Queen Puzzle [closed]

Here's one generalized version of the famous Eight Queen's Puzzle: Given an n × n chess board, and an integer ...
23
votes
5answers
905 views

Fastest Home Prime Generator

What is a home prime? For an example, take HP(4). First, find the prime factors. The prime factors of 4 (in numerical order from least to greatest, always) are 2, 2. Take those factors as a literal ...
9
votes
2answers
456 views

The Tax Historian

Introduction There is a tax collector that has some trouble managing the taxes of his kingdom: the historical records have burnt down in a great fire. He wants to find out how many possible pasts ...
26
votes
2answers
1k views

Fastest Mini-Flak Quine

Mini-Flak is a subset of the Brain-Flak language, where the <>, <...> and [] ...
13
votes
1answer
319 views

Read a crossword with a twist!

Similar to this question, but this is a crossword variation! Instead of only one letter per grid square, you can have one or two. Input: A 2d array, or whatever works in your language. You can ...
27
votes
9answers
4k views

Calculate the permanent as quickly as possible

The challenge is to write the fastest code possible for computing the permanent of a matrix. The permanent of an n-by-n matrix ...
6
votes
1answer
381 views

Help the poor Cryptographers - DLP Edition

Introduction and Motivation I'm mainly active on Cryptography.SE and as such have already stumbled across the question: "How the hell am I supposed tools like cado-nfs to do stuff!?". They are super-...
2
votes
5answers
3k views

The fastest square root calculator

Write a program which outputs the square root of a given number in the shortest time possible. Rules It may not use any builtins or powering with non-integers. Input format as a function argument ...
24
votes
2answers
2k views

Compute the maximum number of runs possible for as large a string as possible

[This question is a follow up to Compute the runs of a string ] A period p of a string w is any positive integer ...
16
votes
3answers
671 views

Find all the Solutions to this Number Puzzle in the Shortest Time Possible

History My company sends out a weekly newsletter to everyone within the company. Included in these newsletters is a riddle, along with a shoutout to whomever in the company was the first to email/...
14
votes
3answers
728 views

Quickly express a number with only 0-9 and the four operations, plus one more extra

Explanation Befunge is a two-dimensional program that uses stacks. That means, to do 5 + 6, you write 56+, meaning: ...