# 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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### How slow is Python really? (Or how fast is your language?)

I have this code which I have written in Python/NumPy ...
19k views

### How Slow Is Python Really (Part II)?

This is a follow up to How slow is Python really? (Or how fast is your language?). It turns out it was a bit too easy to get a x100 speedup for my last question. For those who have enjoyed the ...
13k views

### Fastest semiprime factorization

Write a program to factorize a semi-prime number in the shortest amount of time. For testing purposes, use this: 38!+1 (523022617466601111760007224100074291200000001) It is equal to: ...
1k views

### write a code the find n-th number of Gray Code list [closed]

Write a function that, given N >= 0, finds the Nth number in a standard Gray code. Example input: 1 2 3 4 Example output: ...
9k views

### 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 ...
5k views

### Find the largest prime whose length, sum and product is prime

The number 113 is the first prime whose length 3 is prime, digital sum 5 = 1 + 1 + 3 is ...
2k views

### Extending OEIS: Counting Diamond Tilings

I promise, this will be my last challenge about diamong tilings (for a while, anyway). On the bright side, this challenge doesn't have anything to do with ASCII art, and is not a code golf either, so ...
6k views

### 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 ...
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 ...
2k views

### Fastest Sort in BrainF***

After having implemented QuickSort in BrainF***, I realized it probably wasn't that quick. Operations that are O(1) in normal languages (like array indexing) are significantly longer in BF. Most of ...
967 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 ...
472 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 ...
1k views

### Calculate a probability exactly and quickly

[This is a partner question to Calculate a probability exactly ] This task is about writing code to compute a probability exactly and quickly. The output should be a precise probability written as a ...
2k views

### The making of “Spot It!”: Finding almost unique sets

Puzzle: Find a deck of c cards, each containing p pictures, such that no two pictures match on a given card, and exactly 1 picture on each card matches exactly 1 picture on each of the other cards, ...
6k views

### compute number of 1 bits in a binary representation of a number

The goal is to write a program that returns number of 1 bits in a given number. Examples 5 -> 2 1254 -> 6 56465 -> 8 Winner The winning ...
3k views

### Help Indiana Jones to get the treasure

Story Indiana Jones was exploring a cave where a precious treasure is located. Suddenly, an earthquake happened. When the earthquake ended, he noticed that some rocks that had fallen from the ...
14k views

### Fastest code to find the next prime

The problem is as follows. Input: An integer n Output: The smallest prime bigger than n. The challenge is to give the ...
8k views

### How high can you go? (A coding+algorithms challenge)

Now that everyone has developed their (often amazing) low level coding expertise for How slow is Python really? (Or how fast is your language?) and How Slow Is Python Really (Part II)? it is time for ...
999 views

### Delete some bits and count

Consider all 2^n different binary strings of length n and assume n > 2. You are allowed ...
845 views

### Be an Epidemiologist!

Challenge You must create a simple model of how disease spreads around a group of people. Rules and Requirements The model must be a 1000 by 1000 2D array with each element being a different person....
3k 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 ...
629 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....
812 views

### Probabilities - how high can you go?

I previously asked a question for how to compute a probability quickly and accurately. However, evidently it was too easy as a closed form solution was given! Here is a more difficult version. This ...
573 views

### Too many pawns on a chess board

Given an integer 2n, find the number of possible ways in which 2n^2 black pawns and 2n^2 white pawns can be arranged on a 2n by 2n chess board such that no pawn attack another. A black pawn can ...
1k views

### Finding approximate correlations

Consider a binary string S of length n. Indexing from 1, we can compute the Hamming ...
625 views

### Count the number of Hankelable matrices

Background A binary Hankel matrix is a matrix with constant skew-diagonals (positive sloping diagonals) containing only 0s and 1...
2k views

### Filter a large file quickly

The challenge is to filter a large file quickly. Input: Each line has three space separated positive integers. Output: All input lines A ...
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 ...
18k views

### Super speedy totient function

The goal is simple: calculate the totient function for as many numbers as you can in 10 seconds and sum the numbers. You must print your result at the end and you must actually calculate it. No ...
689 views

### Constructing an Orthogonal-Diagonal Greco-Latin Square

Consider a grid of NxN unique elements. Each element has a letter (from A to the Nth letter,...
503 views

### Biggest square in a grid [closed]

Challenge Given a grid like this, ...
1k views

### Find the maximum determinant for each size Toeplitz matrix

For a fixed n, consider the n by n Toeplitz matrices with entries which are either 0 or 1. The aim is to find maximum determinant over all such Toeplitz matrices. Task For each ...
606 views

### Supersonic domino tilings

Task Write a program that reads three integers m, n either from STDIN or as command-line arguments, prints all possible tilings of a rectangle of dimensions m × n by 2 × 1 and 1 × 2 dominos and ...
1k views

### List prime-factorized natural numbers up to N in ascending order

For a given n list prime factorization of all natural numbers between 1 and n in ascending ...
2k views

### Snakes and Ladders probability of winning

(This is my first Q here, and I don't know much about code golfing.) Your aim is to predict the winner of an ongoing Snakes and Ladders game. INPUT A single number (2-1000) indicating the number of ...
632 views

### Covering Array Validator

A covering array is an N by k array in which each element is one of {0, 1, ..., v-1} (so v ...
14k views

### Solve the Magic Hexagon [closed]

A magic hexagon is a hexagon where every row and every diagonal add up to the same value. In this case the value is 38. Each number from 1 to 19 must be used exactly once. This image shows a solution ...
3k views

### Fastest modular exponentiation

The challenge is to write code in any open source, available on linux, language of your choice to perform modular exponentiation. The input will be two randomly chosen 2048 bit positive integers ...