# 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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### Calculate the number of primes up to n

π(n) is the number of primes less than or equal to n. Input: a natural number, n. Output: π(n). Scoring: This is a fastest-code challenge. Score will be the sum of times for the score cases. I ...
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### 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-$n$ ...
4k views

### High throughput Fizz Buzz

Fizz Buzz is a common challenge given during interviews. The challenge goes something like this: Write a program that prints the numbers from 1 to n. If a number is divisible by 3, write Fizz instead....
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### 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 ...
503 views

### How quickly can you convert an NFA to a DFA?

Convert NFA to DFA as quickly as possible. Input Your input will be an NFA. In order to be able to test your code, it needs to be able to handle an NFA in the following format. This is taken ...
416 views

### Compute the size of intersections of sets

Input A positive integer N representing the size of the problem and four positive integers v, x, y, z. Output This is what your code should compute. Consider a set of N distinct integers and consider ...
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### Fastest unique finder

Given 4096 16-bit integers, only four of which are unique and others appeared twice (so 2050 different integers exist). Find the four uniques. To time precisely and limit RAM usage, your program will ...
3k views

### Fastest draw in the west! [closed]

We're going rootin' tootin' cow-poke shootin! This is a simple contest, first program to draw their pistol wins. How it works: I require 2 things from you, an executable, and a command to be run from ...
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### 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....
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 ...
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### Print all digits of an integer [duplicate]

Challenge Given a positive integer, find the fastest way to iterate over its digits. Bytecode size doesn't matter as much as speed of execution. Examples For 6875, the program would output ...
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### 2D Pathfinding with Momentum

You are piloting a spaceship, outfitted with an engine that can accelerate you at 1km/s^2 in the direction the ship is facing (you have very good inertial dampers). You also have thrusters which can ...
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### Patterns in Permutations

This fastest-code challenge is based partly on this MSE question and exists to extend some OEIS sequences, and create others. If I extend or create sequences based on this challenge, I'll link to this ...
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### Fastest yes in the west

There has been a question about yes in the past, but this one is slightly different. You see, despite yes having a rather long size, it is incredibly fast. Running ...
220 views

### Compute the Three Dimensional Discrete Cosine Transform

Challenge I've checked that there is a question Compute the Discrete Cosine Transform which is a competition for implementing a shortest solution to compute the one dimensional discrete cosine ...
1k views

### Compute all close strings quickly

Input A string S of length between 10 and 16 inclusive. The characters are taken from the 95 printable ASCII characters, byte values 32 (...
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### Sudoku board generator [closed]

A program that randomly generates a Sudoku game board with varying degrees of difficulty (however you decide to measure difficulty). Sudoku requires that there is only one solution, so your program ...
2k views

### Fastest python implementation of multiplication table

I'd be interested to see who can come up with the fastest function to produce multiplication tables, in the following format: ...
831 views

### Box Blur Challenge

The challenge is to implement a box blur in any language. The input will be as a 32-bit uncompressed bitmap, BGRA, preceded by one byte defining the radius of the blur and one byte defining the width ...
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### Fastest alphabetical list sort given the following limitations:

Your function must have an input that takes in an array containing 10000 random names, and must sort these names in alphabetical order. Names have a random length of up to 128 characters. ISO/IEC 8859-...
1k views

### Code-Challenge: Farey sequence (II)

Challenge In this task you would be given an integer N (less than 10^6), output the number of terms in the Farey sequence of order N. The input N < 106 is given in a single line, the inputs ...
899 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 ...
491 views

### Triangles in a tetrahedron

The goal of this challenge is to extend the OEIS sequence A334581. Number of ways to choose $3$ points that form an equilateral triangle from the $\binom{n+2}{3}$ points in a regular tetrahedral ...
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### Square-free semiprime counting

Definition A square-free semiprime is a natural number that is the product of two distinct prime numbers. The task Given a natural number n, count all square-free ...
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### Fast Topswops calculation

From AZSPCS: Suppose you have a deck containing n cards. Each card contains a number from 1 to n, and each number appears on exactly one card. You look at the number on the top card -- let's says it'...
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### No. Of Factors Does the Number Have [duplicate]

Create a function which takes in a input integer and then returns the number of factors it has, like if you pass 25 then it will return ...
159 views

### Sums of permutations of vectors [closed]

I am looking for a more efficient way of computing the following. Let A and B be two vectors of non-negative integers of length <...
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### Crazy Blazin' DOM Injection

Introduction This problem is a challenge that has to do with DOM manipulation at scale and overcoming some issues that may be inherent in dealing with the DOM. This challenge is interesting because ...
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### Fastest player for Dots and Boxes

The challenge is to write a solver for the classic pencil and paper game Dots and Boxes . Your code should take two integers m and ...
478 views

### Number of tilings on a triangular board with triangular tiles

Background Consider the shape $T(n)$ consisting of a triangular array of $\frac{n(n+1)}{2}$ unit regular hexagons: John Conway proved that $n = 12k + 0,2,9,11$ if and only if $T(n)$ can be ...
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### Acyclic orientations of an n-dimensional cube

The goal of this challenge is to check and extend the OEIS sequence A334248: Number of distinct acyclic orientations of the edges of an n-dimensional cube. Take an n-dimensional cube (if n=1, this is ...
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### Hamming distance traveling salesman problem

The Hamming distance between two strings is the number of positions they differ at. You are given a set of binary strings. The task is to find the length of the shortest route that visits all of them ...
396 views

### Spanning paths in a tournament on n nodes

The goal of this challenge is to extend the On-Line Encyclopedia of Integer Sequences (OEIS) sequence A038375. Maximal number of spanning paths in tournament on n nodes. A tournament on $n$ ...
711 views

### Calculate the average longest common substring exactly

[Question inspired by Can you calculate the average Levenshtein distance exactly? . Thank you Anush. ] The longest common substring between two strings is the longest substring which is common to ...
832 views

In this fastest-code challenge, you are provided with a set of $n$ identical blocks and need to determine how many unique buildings can be constructed with them. Buildings must satisfy the following ...
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### 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 ...