Questions tagged [math]
The challenge involves mathematics. Also consider using more specific tags: [number] [number-theory] [arithmetic] [combinatorics] [graph-theory] [geometry] [abstract-algebra].
1,291
questions
-2
votes
1answer
110 views
Symbolic solver [on hold]
First time poster here. Feel free to suggest edits.
Challenge: make a symbolic solver for real algebraic equations.
Required symbols to be recognized are: + - * / = ^ ( ) single-letter variables and ...
35
votes
4answers
3k views
Construct a pentagon avoiding compass use
Rules
You will start with only two elements: Points \$A\$ and \$B\$ such that \$A \neq B\$. These points occupy a plane that is infinite in all directions.
At any step in the process you may do any ...
5
votes
4answers
360 views
Find X,Y,Z coordinates from index
Introduction
I began studying the Collatz Conjecture
And noticed these patterns;
0,1,2,2,3,3...A055086, and 0,1,2,0,3,1...A082375,
in the numbers that go to 1 in one odd step,
5,10,20,21,40,42......
1
vote
1answer
150 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 ...
-4
votes
4answers
90 views
One square root function for unsigned numbers [closed]
One square root function for unsigned numbers
Write the function sqrti(x) that from one not negative integer number x, it returns the integer square root of that number truncate to the 0 digit, so ...
4
votes
0answers
90 views
Make a slow monotonic injection [duplicate]
In 256 bytes or fewer write a function, \$f\$, from the positive integers to the positive integers that is:
Monotonic: larger inputs always map to larger outputs. (\$a < b \implies f(a) < f(b)\$...
5
votes
2answers
281 views
23
votes
19answers
2k views
Analog is Obtuse!
An analog clock has 2 hands*: Hour and minute.
These hands circle the clock's face as time goes by. Each full rotation of the minute hand results in 1/12th of a rotation of the hour hand. 2 full ...
10
votes
22answers
2k views
Find the C-factor of a vote
In this challenge you will be determining how controversial a vote is, given an array of other votes, by figuring out a number called the C-factor. What is the C-factor, you ask?
Well, imagine you've ...
8
votes
1answer
262 views
Partition and Restructure
Given two contiguous shapes of the same area, determine the optimal way to divide the first shape into a minimum number of contiguous segments such that they can be rearranged to form the second shape....
11
votes
18answers
801 views
An OEIS polyglot
This is an answer-chaining challenge relating to the OEIS.
Oh, the justification for this is because a company needs one program to print out their OEIS sequences real bad and they have every ...
91
votes
12answers
8k views
Proving that a Russian cryptographic standard is too structured
The aim of this challenge is to find an impossibly short
implementation of the following function p, in the langage of your
choosing. Here is C code implementing it ...
3
votes
1answer
201 views
Multiplication in the Steenrod Algebra
Here's yet another Steenrod algebra question. Summary of the algorithm: I have a procedure that replaces a list of positive integers with a list of lists of positive integers. You need to repeatedly ...
16
votes
11answers
1k views
Generate basis elements of the Steenrod algebra
The Steenrod algebra is an important algebra that comes up in algebraic topology. The Steenrod algebra is generated by operators called "Steenrod squares," one exists for each positive integer i. ...
20
votes
16answers
3k views
Cuban Primes
Given a natural number \$n\$, return the \$n\$-th cuban prime.
Cuban Primes
A cuban prime is a prime number of the form
$$p = \frac{x^3-y^3}{x-y}$$
where \$y>0\$ and \$x = 1+y\$ or \$x = 2+y\$
...
0
votes
3answers
198 views
Roots of Arbitrary Numbers [closed]
One day, when I was bored in maths class, I learned of a neat trick for solving the real cube root of a number!
Let's use the number \$79,507\$ as an example.
First, take digit in the one's place ...
14
votes
16answers
599 views
Dihedral group D4 composition with custom labels
The dihedral group \$D_4\$ is the symmetry group of the square, that is the moves that transform a square to itself via rotations and reflections. It consists of 8 elements: rotations by 0, 90, 180, ...
12
votes
13answers
2k views
A factorization game
Input
A single integer \$1 \leq x \leq 10^{15}\$.
Output
The maximum number of distinct positive integers that have the product \$x\$.
Examples
Input: 1099511627776. Output: 9. One possible ...
22
votes
23answers
3k views
Upside-Down Pyramid Addition…REVERSED!
Upside-Down Pyramid Addition is the process of taking a list of numbers and consecutively adding them together until you reach one number.
When given the numbers ...
16
votes
22answers
919 views
Enumerate Derangements
Given some positive integer \$n\$ generate all derangements of \$n\$ objects.
Details
A derangement is a permutation with no fixed point. (This means in every derangement number \$i\$ cannot be in ...
32
votes
21answers
2k views
A Note on N!
J. E. Maxfield proved following theorem (see DOI: 10.2307/2688966):
If \$A\$ is any positive integer having \$m\$ digits, there exists a positive integer \$N\$ such that the first \$m\$ digits of \$...
10
votes
6answers
1k views
Which really big number is bigger?
This question is tricky (and in particular harder than Which big number is bigger?), for those who like more challenging puzzles.
Input
Integers a1, a2, a3, a4, a5, b1, b2, b3, b4, b5 each in the ...
35
votes
21answers
4k views
Amount of permutations on an NxNxN Rubik's Cube
Introduction:
A 3x3x3 Rubik's Cube has \$43,252,003,274,489,856,000\$ possible permutations, which is approximately 43 quintillion. You may have heard about this number before, but how is it actually ...
24
votes
21answers
2k views
Fundamental Solution of the Pell Equation
Given some positive integer \$n\$ that is not a square, find the fundamental solution \$(x,y)\$ of the associated Pell equation
$$x^2 - n\cdot y^2 = 1$$
Details
The fundamental \$(x,y)\$ is a pair ...
1
vote
0answers
151 views
How many right triangles can you find? [closed]
Challenge
You will be given an input represented by x, which is a string containing at least 3 characters. It will consist only of the standard numeric characters, ...
14
votes
14answers
1k views
Multiply Two Integer Polynomials
Your task is to take two single-variable integer polynomial expressions and multiply them into their unsimplified first-term-major left-to-right expansion (A.K.A. FOIL in the case of binomials). Do ...
0
votes
0answers
100 views
Compute the order of a Rubik's Cube cycle without trivially counting them [duplicate]
On a Rubik's Cube, performing a particular sequence of moves repeatedly will always return it to its original state. Your job is to figure out the "order" of a particular sequence of moves, that is, ...
-1
votes
2answers
119 views
Find efficient seating arrangement in a line [closed]
We have X Girls and Y Boys in a class. If more girls sit together they will not behave. Similarly if more boys sit together they will not behave.
Write a program/algorithm to get maximum same gender ...
39
votes
19answers
5k views
Calculate the Mean mean of two numbers
disclaimer: the Mean mean is made up by me
Define the arithmetic mean of \$n\$ numbers as
$$M_1(x_1,...,x_n)=\frac{x_1+x_2+...+x_n}{n}$$
Define the geometric mean of \$n\$ numbers as
$$M_0(x_1,...,...
1
vote
4answers
263 views
Nearest hamming cycle period in MD5
This riddle was inspired by that thread. Consider that you are super-hacker and try to break MD5 hashing algorithm by looking for a hash collisions for a given hash string which your friend gave to ...
15
votes
2answers
293 views
Japanese Multiplication [duplicate]
There's a visual method for multiplication that is taught to Japanese schoolchildren [citation needed] that uses lines and crossings to get the answer.
Image Source
Your task is to implement this in ...
44
votes
47answers
4k views
Multiplicative persistence
Multiplicative Persistence
Multiply all the digits in a number
Repeat until you have a single digit left
As explained by Numberphile:
Numberphile "What's special about 277777788888899?"
Numberphile ...
2
votes
1answer
175 views
Find all diagonal counts in only one direction [closed]
If I need to get the number of diagonal squares in all directions:
I do the following formula 2 N − 2 − |x − y| − |x + y − N − 1|
The above example has 13 and ...
22
votes
1answer
1k views
Is it possible to make a clamp function shorter than a ternary in JS?
Imagine this short function to clamp a number between 0 and 255:
c = n => n > 0 ? n < 255 ? n : 255 : 0
Is this the shortest possible version of a clamp ...
25
votes
28answers
3k views
Make me a metasequence
Background
For this challenge, a 'metasequence' will be defined as a sequence of numbers where not only the numbers themselves will increase, but also the increment, and the increment will increase ...
15
votes
16answers
622 views
Compound Interest… with Wizard Money
Gringotts isn't just a vault, but a reputable financial institution and wizards need loans too. Since you don't want to be screwed over by the Gringotts goblins, you decided it would be a good idea to ...
33
votes
5answers
8k views
Historical difference between `/` and `÷` in mathematical expressions
Introduction:
Inspired by a discussion that is already going on for many years
regarding the expression \$6÷2(1+2)\$.
With the expression \$6÷2(1+2)\$, mathematicians will quickly see that ...
7
votes
7answers
535 views
Check type of an integer
You will receive an integer less than 2000000000 and bigger than -2000000000 and you have to test what type(s) of number this is out of:
...
10
votes
10answers
561 views
Fizzbuzz in any base
Challenge
Input:
An integer \$b\$ between 2 and 62 (inclusive).
Output:
Count from \$1\$ to the equivalent of \$5000_{10}\$ in base \$b\$, using any reasonable representation for the digits.
...
21
votes
12answers
1k views
Indexing the Extended Fibonacci Numbers
You've probably heard of Fibonacci numbers. Ya know, that integer sequence that starts with 1, 1, and then each new number is the sum of the last two?
...
6
votes
5answers
295 views
Generate the k-ary necklaces of length n
The set of necklaces is the set of strings, where two strings are considered to be the same necklace if you can rotate one into the other. Your program will take nonnegative integers ...
1
vote
2answers
205 views
Work out \$x^y\$ using only addition and subtraction [duplicate]
The challenge is to implement a function or program that takes two numbers, \$x\$ and \$y\$ and return the result of \$x^y\$.
The program cannot use any other mathematical operation other than \$+\$ ...
5
votes
1answer
316 views
Surreal Numbers
Surreal Numbers
Surreal numbers are one way of describing numbers using sets. In this challenge you will determine the value of a surreal number.
Intro
A surreal number consists of two sets: a left ...
9
votes
0answers
113 views
Order of Elements of the Rubik's Cube [duplicate]
Introduction
All the possible moves and their combinations of a Rubik's Cube form a group. A group in general is a set with some binary operation defined on it. It must contain a neutral element with ...
0
votes
0answers
46 views
Polynomial to String [duplicate]
I'm new to code-golf, but I was trying to solve this problem myself, and thought there must be a much "better"/shorter way of doing it.
Given a sequence (list) of numbers \$a_0, a_1,\cdots,a_n\$, ...
2
votes
3answers
135 views
All the digisibles [duplicate]
A natural number (written in the decimal base) is qualified as digisible if and only if it fulfills the following 3 conditions:
none of its digits is zero,
all the digits that compose it are ...
20
votes
20answers
1k views
Smallest Diversifying Exponent
A pandigital number is an integer which contains every digit from 0 to 9 at least once. 1234567890, 1902837465000000, and 9023289761326634265 are all pandigital. For the purposes of this challenge, ...
14
votes
25answers
1k views
Standardize the Samples (Compute the z-Score)
Given a list of floating point numbers, standardize it.
Details
A list \$x_1,x_2,\ldots,x_n\$ is standardized if the mean of all values is 0, and the standard deviation is 1. One way to compute this ...
-2
votes
2answers
150 views
find the value at kth position when numbers are sorted lexicographically till n [closed]
Ex :-
Input:
n = 12, k = 5
Output:
ans = 2
Sorted list S: ["1", "10", "11", "12", "2", "3", "4", "5", ...., "9"]
ans = 2
1
vote
4answers
201 views
Round the digits last digit, over and over
Challenge:
Given two inputs, x and y, round x to one less significant figure, then repeat until it has y number of unrounded digits left. (the decimal point does not count as a digit)
Input & ...
