# Questions tagged [math]

The challenge involves mathematics in some central way. Also consider using more specific tags, listed in the tag wiki info.

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### Product of Digits

For a given positive integer number N, write a complete program to find the minimal natural M such that the product of digits of M is equal N. N is less than 1,000,000,000. If no M exists, print -1. ...
1k views

### Build a small and balanced mobile

You are given a bunch of weights, and your task is to build a small balanced mobile using those weights. The input is a list of integer weights in the range 1 through 9, inclusive. There may be ...
2k views

### Amicable number calculator [closed]

Write a program that calculates amicable numbers, starting from [0,0], intil the maximum value for an integer is reached in the language you chose to write it in. Amicable numbers are two different ...
4k views

### Circle Through Three Points

Given the Cartesian coordinates of three points on a plane, find the equation of the circle through them all. The three points will not be on a straight line. Each line of input to your program will ...
661 views

### Calculate an integer sequence derived from prime factors

Create a function, expression, or program which does the following: Take the prime factors of any number and sum them. For example, the prime factors of 28 are 2 2 7, summed to 11. Multiply the ...
2k views

### Determine if a polygon is convex

Write a program to determine if the input polygon is convex. The polygon is specified with one line containing N, the number of vertices, then N lines containing the x and y coordinates of each ...
8k views

### For 2 arrays, subtract every element in one array from the position-matching element in the other [closed]

For 2 arrays each with X elements, what is the SHORTEST code to subtract every element in the second from every element in the first, 1 to 1 so, for example: A1 = [10,11,12] A2 = [1,2,3] A1 "-" A2 ...
3k views

### Long multiply, 8 bits at a time

You are given a 16-bit machine and told to implement multiplication of arbitrary-sized integers. Your registers can only hold 16-bit numbers, and the biggest multiply instruction takes two 8-bit ...
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 ...
775 views

### Sum of Fibonacci numbers

I found this task here. Given the ith (1<=i<=35) Fibonacci number F(i) calculate the sum of the ith till i+9th number F(i)+F(i+1)+...+F(i+9) and the last digit of the i+246th one F(i+...
626 views

### Find all Super Powers [duplicate]

A positive number is said to be super power when it is the power of at least two different positive integers. Write a program that lists all super powers in the interval [1, 264) (i.e. between 1 (...
2k views

### Fastest algorithm for decomposing a perfect power

A perfect power is a positive integer that's equal to one positive integer, to the power of another positive integer (e.g. ab is a perfect power). Note that trivial solutions (e.g. b=1) are excluded; ...
2k views

### Non trivial powers

Write the shortest program to print the non-trivial powers ≤ 2^12 in order non-trivial power means the base and exponent are > 1 Leading whitespace is optional When there are multiple solutions, ...
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 ...
1k views

### Code golf: Distributing the balls (I)

Challenge In this task you have compute the number of ways we can distribute A balls into B cells with with every cell having at-least one ball. The inputs A and B are given in a single ...
1k views

### Code-Golf: Farey sequence (I)

Challenge In this task you would be given an integer N (less than 10^5), output the Farey sequence of order N. The input N is given in a single line,the inputs are terminated by EOF. Input <...
895 views

### The last digit in an exponentation

In this task you will be given A (less than 10000 digits long) and B (less than 2^64), and you will need to compute the last digit of (A · A · A · ... · A (B times)). The ...
7k views

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 ...
6k views

### Count number of hefty decimals between 2 numbers [closed]

Let's say we have a non-negative integer that is "hefty" (that is, "heavy") if its average digit value is greater than 7. The number 6959 is "hefty" because: (6 + 9 + 5 + 9) / 4 = 7.5 The number ... 1k 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 ...
3k views

### Decompose a permutation into cycles

There is a well-known theorem that any permutation can be decomposed into a set of cycles. Your job is to write the shortest possible program to do so. Input: Two lines. The first contains a ...
1k views

### Floating point addition, without floats!

Your task is to write a program, in any language, that adds two floating point numbers together WITHOUT using any fractional or floating point maths. Integer maths is allowed. Format The format for ...
3k views

### Compute the first N digits of e

Challenge Write a program to compute the the first N (<= 10^3) digits of e. Your program should take an integer N as input. Input: 100 Output: ...
441 views

### The fourth power (Juzuk) [closed]

In 1939 Juzuk described a way to generate the fourth powers of natural numbers. Group the natural numbers like this: ...
615 views

### Permutation group operation

There is a well-known bijection between the permutations of $n$ elements and the numbers $0$ to $n!-1$ such that the lexicographic ordering of the permutations and the corresponding numbers is ...
12k views

### Determine if 4 points form a square

Write a function that takes 4 points on the plane as input and returns true iff the 4 points form a square. The points will have integral coordinates with absolute values < 1000. You may use any ...
678 views

### GolfScript - The missing function

The GolfScript language has one serious lack, no float or fixed point handling. Remedy this by creating a function F for converting an integer number, given as a string, to a string representing 1 / ...
813 views

### Code Golf: Number of paths!

Challenge Consider a square matrix of order N(N rows and N columns). At each step you can move one step to the right or one step to the top. How many possibilities are to reach (N,N) from ...
394 views

### Rotate Cartesian coordinates.

Write a program rotates some Cartesian coordinates through an angle about the origin (0.0,0.0). The angle and coordinates will be read from a single line of stdin in the following format: ...
854 views

### Break the broken cipher [closed]

I have designed a simple random generator that cycles two numbers in a chaotic way using a multiply and modulus method. It works great for that. If I were to use it as a cipher generator it would ...
951 views

### Calculate probability of getting half as many heads as coin tosses.

Write a program that, given a small positive even integer from standard input, calculates the probability that flipping that many coins will result in half as many heads. For example, given 2 coins ...
4k views

### My Word can beat up your Word

PROBLEM Given two words, find the winner in a digital root battle. Define the digital root of a word this way: Each letter of the alphabet is assigned a number: A = 1, B = 2, C = 3, ..., Z = 26 ...
1k views

### How many switches are ON

A class has N student and the class room has N switches (all turned OFF and numbered 1 to N). Each student has an enrollment number assigned from 1 to N. Each student serially (by number) toggles the ...
577 views

### Physics golf: inclined shooting

An angry bird is shot at an angle $β$ to the horizontal at a speed $u$. The ground is steep, inclined at an angle $α$. Find the horizontal distance $q$ that the bird traveled before it hit the ...
900 views

### Modulo code golf

Write a function f(a,b) that returns a mod b given the constraints: you can't use division in any way ...
716 views

### Implement BCD Arithmetic

Write the shortest function you can that takes two binary-coded decimal integers and a character indicating an arithmetic operation to perform and return the result. Input Specification You will be ...
2k views

### Polynomial Long Division

Implement polynomial long division, an algorithm that divides two polynomials and gets the quotient and remainder: (12x^3 - 5x^2 + 3x - 1) / (x^2 - 5) = 12x - 5 R 63x - 26 In your programs, you will ...
3k views

### Roman numeral converter function

Create the shortest function to convert a string of Roman numerals to an integer. The rules for each letter can be found at the Wikipedia page. Letters above 1,000 will have parentheses placed ...
5k views

### Last non-zero digit of n!

Given an integer 1 ≤ N ≤ 1,000,000 as input, output the last non-zero digit of N!, where ! is the factorial (the product of all numbers from 1 to N, inclusive). This is OEIS sequence A008904. Your ...
3k views

### Multiply without multiply [closed]

Write the fastest (best big-O) and smallest multiplication algorithm for positive integers, without using multiplication operators. You are only allowed addition, subtraction, logical functions (AND, ...
2k views

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 ...
4k 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/...
632 views

### Perfect powers in more than one way?

Challenge Your task is to write a program or function which, given a positive integer $N$, finds all positive integers less than or equal to $N$ that can be expressed as a perfect power in more ...
117 views

### Five aligned points and some of the pairwise distances. Infer the relative positions! [closed]

Given five points on a straight line such that their pairwise distances are 1,2,4, ..., 14,18,20 (after ordering), find the respective positions of the five points (relative to the furthest point on ...
10k 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 ... 864 views

### Compute modular inverse

Given two positive numbers $x$ and $n$ with $x<2^n$, write the shortest possible function to compute $x^{-1} \mod 2^n$. In other words, find $y$ such that $xy=1 \mod 2^n$. Your ...
3k views

### Test if a given number is a Vampire Number [duplicate]

EDIT: In the interest of increasing the complexity, i've added more to the challenge. In mathematics, a vampire number (or true vampire number) is a composite natural number v, with an even ...
262 views

### Sharing Inherited Land [closed]

You and your brother have inherited a rectanglar block of land. This block of land's corners are read in from stdio as TLX,TLY,TRX,TRY,BLX,BLY,BRX,BRY (all decimal ...