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Questions tagged [math]

The challenge involves mathematics. Also consider using more specific tags: [number] [number-theory] [arithmetic] [combinatorics] [graph-theory] [geometry] [abstract-algebra].

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33
votes
50answers
6k views

Generate Pascal's triangle

Pascal's triangle is generated by starting with a 1 on the first row. On subsequent rows, the number is determined by the sum of the two numbers directly above it to the left and right. To ...
15
votes
15answers
2k views

Golf the Subset-Sum Problem

Task Given a list of space-delimited integers as input, output all unique non-empty subsets of these numbers that each subset sums to 0. Test Case Input: ...
59
votes
39answers
12k views

Find the Smoothest Number

Your challenge is to find the smoothest number over a given range. In other words, find the number whose greatest prime factor is the smallest. A smooth number is one whose largest prime factor is ...
33
votes
18answers
7k views

Find the nth decimal of pi

There are already 30 challenges dedicated to pi but not a single one asks you to find the nth decimal, so... Challenge For any integer in the range of ...
29
votes
28answers
3k views

Josephus problem (counting out)

The challenge Write a function that takes two positive integers n and k as arguments and returns the number of the last person remaining out of n after counting out each k-th person. This is a code-...
66
votes
95answers
9k views

Collatz Conjecture (OEIS A006577)

This is the Collatz Conjecture (OEIS A006577): Start with an integer n > 1. Repeat the following steps: If n is even, divide it by 2. If n is odd, multiply it by 3 and add 1. It is proven that ...
27
votes
16answers
2k views

Compute the multinomial coefficient

Time for another easy challenge in which all can participate! The multinomial theorem states: The expression in parentheses is the multinomial coefficient, defined as: Allowing the terms ki to ...
393
votes
156answers
243k views

Write a program that makes 2 + 2 = 5 [closed]

Write a program that seemingly adds the numbers 2 and 2 and outputs 5. This is an underhanded contest. Your program cannot output any errors. Watch out for memory holes! Input is optional. ...
41
votes
43answers
7k views

Reverse Polish notation

You must evaluate a string written in Reverse Polish notation and output the result. The program must accept an input and return the output. For programming languages that do not have functions to ...
37
votes
8answers
4k views

Shortest terminating program whose output size exceeds Graham's number

Write the shortest possible program (length measured in bytes) satisfying the following requirements: no input output is to stdout execution eventually terminates total number of output bytes exceeds ...
53
votes
73answers
7k views

Test a number for narcissism

A Narcissistic Number is a number which is the sum of its own digits, each raised to the power of the number of digits. For example, take 153 (3 digits): 13 + 53 + 33 = 1 + 125 + 27 = 153 1634: ...
25
votes
8answers
1k views

All your bijective base are belong to us

Background A bijective base b numeration, where b is a positive integer, is a bijective positional notation that makes use of b symbols with associated values of 1 to b. Unlike its non-bijective ...
43
votes
37answers
15k views

Draw A Sierpinski Triangle

The Sierpinsky Triangle is a fractal created by taking a triangle, decreasing the height and width by 1/2, creating 3 copies of the resulting triangle, and place them such each triangle touches the ...
63
votes
150answers
13k views

Sum of all integers from 1 to n

I'm honestly surprised that this hasn't been done already. If you can find an existing thread, by all means mark this as a duplicate or let me know. Input Your input is in the form of any positive ...
28
votes
5answers
2k views

Advanced Calculator

You must write a program that evaluates a string that would be entered into an advanced calculator. The program must accept input using stdin and output the correct answer. For languages that do no ...
40
votes
65answers
5k views

Greatest Common Divisor

Your task is to compute the greatest common divisor (GCD) of two given integers in as few bytes of code as possible. You may write a program or function, taking input and returning output via any of ...
28
votes
37answers
4k views

Implement hyperexponentiation/tetration without the use of '^'

The Challenge Implement tetration (aka Power Tower or Hyperexponentiation) with the least amount of characters. The Conditions Don't use the 'power' operator or its equivalents (such as ...
22
votes
11answers
4k views

Generate a Kolakoski sequence [duplicate]

Definition1 A Kolakoski sequence is a self-describing infinite sequence {kn} of alternating blocks of 1's and 2's, given by the following rules: k0 = 1 kn = the length of the (n+1)'th ...
32
votes
16answers
5k views

Balanced Ternary Converter

Credits for the challenge idea go to @AndrewPiliser. His original proposal in the sandbox was abandoned and since he has not been active here for several months, I have taken over the challenge. ...
47
votes
6answers
7k views

Golf a number bigger than TREE(3)

The function TREE(k) gives the length of the longest sequence of trees T1, T2, ... where each vertex is labelled with one of k colours, the tree Ti has at most i vertices, and no tree is a minor of ...
21
votes
3answers
2k views

Four fours puzzle

The Four fours puzzle is a popular recreational mathematical puzzle that involves using exactly four 4s (and no other number) and a defined set of operations to reach every number from 0 to a given ...
19
votes
19answers
3k views

Basic Calculator

You must write a program to evaluate a string that would be entered into a calculator. The program must accept input and output the correct answer. For languages that do not have standard input/...
33
votes
22answers
7k views

XOR multiplication

You goal is to implement the operation of XOR (carryless) multiplication, defined below, in as few bytes as possible. If we think of bitwise XOR (^) as binary ...
35
votes
28answers
3k views

Find the number in the Champernowne constant

Introduction In base 10, the Champernowne constant is defined by concatenating representations of successive integers. In base 10: 0.1234567891011121314151617... ...
19
votes
14answers
1k views

Discrete Convolution or Polynomial Multiplication

Given two non empty lists of integers, your submission should calculate and return the discrete convolution of the two. Interestingly, if you consider the list elements as coefficients of polynomials, ...
12
votes
4answers
974 views

Polynomial Interpolation

Write a program that performs Polynomial Interpolation using true arbitrary precision rational numbers. The input looks like this: f(1) = 2/3 f(2) = 4/5 f(3) = 6/7 ... You may assume that there's ...
330
votes
55answers
103k views

Tweetable Mathematical Art [closed]

Integer math can generate amazing patterns when laid out over a grid. Even the most basic functions can yield stunningly elaborate designs! Your challenge Write 3 Tweetable (meaning 140 characters ...
95
votes
346answers
16k views

One OEIS after another

As of 13/03/2018 16:45 UTC, the winner is answer #345, by Scrooble. This means the contest is officially over, but feel free to continue posting answers, just so long as they follow the rules. As ...
44
votes
66answers
6k views

It's Hip to be Square

Challenge So, um, it seems that, while we have plenty of challenges that work with square numbers or numbers of other shapes, we don't have one that simply asks: Given an integer ...
51
votes
43answers
5k views

Coprimes up to N

Given a number n >= 2, output all the positive integers less than n where gcd(n, k) == 1 (...
31
votes
42answers
3k views

Least Common Multiple

The least common multiple of a set of positive integers A is the smallest postive integer B such that, for each ...
54
votes
35answers
6k views

Print the N-bonacci sequence

This isn't very widely known, but what we call the Fibonacci sequence, AKA 1, 1, 2, 3, 5, 8, 13, 21, 34... is actually called the Duonacci sequence. This is ...
25
votes
11answers
3k views

Generate a pair of integers from a non-negative one

You should write a program or function which takes a non-negative integer N as input and outputs or returns two integers (negative, zero or positive) ...
24
votes
38answers
3k views

Reimplementing square root [duplicate]

Define a function, s, which takes a number and returns the square root. No use of library functions, such as Java's Math.sqrt() or PHP's built in sqrt(), allowed.
20
votes
1answer
837 views

Factor a polynomial over a finite field or the integers

Without using any built-in factoring/polynomial functions, factor a polynomial completely into irreducibles over the integers or a finite field. Input Your program/function will receive some prime (...
11
votes
1answer
2k views

Generate a number by using a given list of numbers and arithmetic operators

You are given a list of numbers L = [17, 5, 9, 17, 59, 14], a bag of operators O = {+:7, -:3, *:5, /:1} and a number ...
45
votes
42answers
3k views

Count sums of two squares

Given a non-negative number n, output the number of ways to express n as the sum of two squares of integers ...
26
votes
22answers
1k views

Natural construction

The natural numbers including 0 are formally defined as sets, in the following way: Number 0 is defined as the empty set, {} For n ≥ 0, number n+1 is defined as n ∪ {n}. As a consequence, n = {0, 1, ...
19
votes
2answers
792 views

Dames, do some math!

The order of operations, PEMDAS, is a basic rule in mathematics telling us which order operations should be performed: "Parentheses, Exponents, Multiplication and Division, and Addition and ...
13
votes
7answers
2k views

What is the average of n, the closest prime to n, the square of n and the closest Fibonacci number to n?

This is a math problem which takes quite many things into question, making it rather challenging, and as you might have guessed, it's a code golf, so it should be as short as possible as well. The ...
22
votes
15answers
1k views

Calculate the partitions of N

Your challenge is simple: GIven an integer N, ouput every list of positive integers that sums to N. For example, if the input was 5, you should output ...
151
votes
4answers
13k views

Hyperprogramming: N+N, N×N, N^N all in one

Write a program that takes in a number N from 1 to 9 inclusive. In its native form your program should output N+N. E.g. output 2 if N is ...
40
votes
55answers
4k views

An abundance of integers!

An Abundant number is any number where the sum of its proper divisors is greater than the original number. For example, the proper divisors of 12 are: ...
30
votes
11answers
1k views

Print, Increment, Decrement, Alias - Interpret Prindeal

Prindeal (pronounced prin-dee-al) is a new esoteric programming language that only has four commands: print, increment, decrement, and alias. Despite its minimalism, complex mathematical operations ...
29
votes
24answers
4k views

How Many Rectangles in the Grid?

Well, although this challenge turned out to be a huge success, it also turned out to be very trivial to solve. Therefore, for those of looking for more of a challenge, I created a sequel to this ...
28
votes
25answers
4k views

Index of a multidimensional array

Lower level languages, such as C and C++ actually have no concept of multidimensional arrays. (Other than vectors and dynamic arrays) When you create a multidimensional array with ...
25
votes
49answers
3k views

Factorial digit sum

The challenge is to calculate the digit sum of the factorial of a number. Example Input: 10 Output: 27 10! = 10 × 9 × ... × 3 × 2 × 1 = 3628800, and the sum of ...
23
votes
32answers
2k views

Convert a number to Hexadecimal

Challenge Here's a simple one. Write a function or program when given a number in base 10 as input, it will return or print that number's value in Hexadecimal. Examples ...
67
votes
141answers
7k views

Output the sign

Given a number N, output the sign of N: If N is positive, output 1 If N is negative, output -1 If N is 0, output 0 N will be an integer within the representable range of integers in your chosen ...
20
votes
38answers
4k views

Additive Persistence

The shortest code to pass all possibilities wins. In mathematics, the persistence of a number measures how many times a certain operation must be applied to its digits until some certain fixed ...