Questions tagged [number]
A competition to solve a particular problem through the usage and manipulation of numbers.
1,211
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answers
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There's more than one way to skin a set
Given a set of positive integers \$ S \$, output the set of all positive integers \$ n \$ such that \$ n \$ can be made by summing a subset of \$ S \$ in more than one different way, i.e., that are ...
- 18.2k
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votes
18
answers
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Palindromic Powers
Powers
We define an important power as a number that can be represented as \$ x^y \$ where \$ x ≥ 2 \$ and \$ y ≥ 2 \$.
Palindrome
We define an ...
- 471
20
votes
8
answers
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ASCII-Art n'th Root
Challenge:
Given two integers \$a\$ and \$b\$, with lengths \$A=length(a), B=length(b)\$, output an ASCII-art of the \$a^{th}\$ root of \$b\$, including the answer rounded to \$A\$ amount of decimal ...
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14
votes
6
answers
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views
Rounding a range
You have a line with two endpoints a and b (0 ≤ a < b) on a 1D space. When ...
- 2,101
22
votes
9
answers
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Sequence of integers not the sum of powers of earlier terms
Starting with 1, output the sequence of integers which cannot be represented as the sum of powers of earlier terms. Each previous term can be used at most once, and the exponents must be non-negative ...
- 411
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votes
18
answers
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Words with Easy Letters in a Word Search
Introduction:
Apparently I keep coming up with word search related challenges lately. :)
When I do the word search in the Dutch news paper, some words are very easy to find because they contain ...
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14
votes
13
answers
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Average-ignorant sets of integers
Recently a friend of mine posed the following:
What subset of the integers satisfies the condition if distinct a and b are in the subset, their average is not in the subset? I know the set of non-0 ...
- 491
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votes
35
answers
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Find the weight of five apples
Problem
John bought 5 apples. You are given the weights of every group of four apples, and must then find the weights of the apples themselves.
For example, if all apples without the first one weigh ...
- 99
17
votes
17
answers
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Numbers in 2050
It's 2050, and people have decided to write numbers in a new way. They want less to memorize, and number to be able to be written quicker.
For every place value(ones, tens, hundreds, etc.) the number ...
- 303
5
votes
6
answers
534
views
Batt to the Basics
One of your acquaintances has a hobby of making make-shift electrical gadgets using various types of batteries. However, since they're thrifty, they want to use as few batteries as possible for their ...
- 575
14
votes
17
answers
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The interstice of two binary numbers
Given two integers, compute the two numbers that come from the blending the bits of the binary numbers of equal length(same number of digits, a number with less digits has zeros added), one after the ...
- 457
10
votes
8
answers
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How many times do I break my own rule?
Introduction:
In my recent Strikethrough the Word Search List challenge I mentioned the following:
When I do the word-search puzzles, I (almost) always go over the words in order, and strike them ...
- 103k
3
votes
9
answers
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views
int, float or neither?
Given a string, determine if it is an int, a float or neither.
Examples
123 - int
62727.0033 - float
644c.33 - neither
Your code should output a different value depending on which it is. For example ...
- 179
22
votes
17
answers
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views
Pairs of integers ordered by their exponentiation
Output the infinite list of pairs of integers (a, b), where both \$ a > 1 \$ and \$ b > 1 \$, ordered by the value of \$ a^b \$. When there are multiple pairs ...
- 18.2k
25
votes
27
answers
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Fill in the next numbers
Given a list of integers, output a list where the \$ i \$th element of the list equals the first number in the input list which is \$ \ge i \$, until there are no such numbers.
For example, if the ...
- 18.2k
14
votes
14
answers
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views
Lexicographically Smallest Decreasing Integer Partition
For a given number n, output an strictly decreasing array whose sum is n and its lexicographical order is the smallest for any ...
- 3,031
8
votes
7
answers
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views
Factorials of primes decomposition
You have to decompose a positive integer/fraction as a product of powers of factorials of prime numbers.
For example
...
- 3,031
12
votes
11
answers
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Output two numbers (Robbers' thread)
This is the robbers' thread to a cops-and-robbers challenge. Click the link to find the cops' thread.
In the cops' thread of this challenge, answerers will be writing programs which output two ...
- 84.5k
23
votes
20
answers
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Output two numbers (Cops' thread)
This is the cops' thread to a cops-and-robbers challenge. Click the link to find the robbers' thread.
The challenge here is very simple. Create two programs of the same size, in the same language, ...
- 84.5k
17
votes
28
answers
1k
views
Reversed Multiple Pair
Intro
Two numbers are a reversed multiple pair if they satisfy the following property:
$$
a\cdot b = \operatorname{reversed}( (a-1)\cdot b )
$$
Here, \$\operatorname{reversed}()\$ means to reverse the ...
- 3,053
11
votes
18
answers
817
views
Move to Right and left
Task
Your task is to take an array of numbers as input, and produce a new one where each number has been shifted both right and left, leaving 0s if no number fills ...
- 2,493
6
votes
1
answer
188
views
Represent any integer with an expression that uses no digit besides '4' [closed]
Fourward (Introduction)
I have an unhealthy obsession with the number 4. I love it so much, in fact, that seeing any other digit is frustrating to me. I therefour wish to create a 'Fourier ...
- 69
-6
votes
4
answers
150
views
Indices of square numbers that are also pentagonal [closed]
First 15 numbers of the A046173:
...
- 3,031
23
votes
27
answers
2k
views
Next Greater Number
Given an integer n, find the next number that follows the following requirements
The next greater number is a number where each digit, from left to right, is ...
- 3,031
16
votes
13
answers
997
views
Number of complete rhyme schemes
A rhyme scheme is the pattern of rhymes at the end of the lines in a poem. They are typically represented using letters, like ABAB. We consider two rhyme schemes ...
- 18.2k
18
votes
1
answer
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views
Largest SKI output in less than 200 combinators
The Challenge
Create an terminating expression in SKI Combinator Calculus in less than 200 combinators (S, K, I) that reduces to the expression with the most combinators.
There will be no limit on how ...
- 703
8
votes
17
answers
787
views
Minimum difference between cartesian product of 3 elements that add up to a certain number
Let's say I've got a list (or array) of:
l = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
I want to get the third Cartesian power of the above list, where we take every ...
- 1,099
21
votes
17
answers
855
views
Kolmogorov-simple numbers
If you visit Code Golf often, you may have heard of Kolmogorov complexity. It's usually defined as the amount of bytes required to express some string in a programming language.
Here the Kolmogorov-...
- 6,645
29
votes
12
answers
1k
views
Nth FizzBuzz Number
Introduction
Everyone knows the FizzBuzz sequence. It goes something like this:
1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz
.
.
.
In case you don't ...
- 3,053
28
votes
25
answers
2k
views
Converge to a number
Your challenge is to, given a positive integer n, count up to each digit of it, giving the effect of converging on it.
Basically, count up to the first digit of n by its place value (\$⌊\log_{10}\left(...
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16
votes
11
answers
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Write a number in overflowed binary
We all know how binary conversion works: the sequence of bits
$$ b_1, b_2, ..., b_{n-1}, b_n $$
encodes the number
$$ b_1 \times 2^{n-1} + b_2 \times 2^{n-2} + ... + b_{n-1} \times 2^1 + b_n \times 2^...
- 18.2k
-1
votes
6
answers
221
views
Check for Wonky numbers [closed]
Task :
Wonky numbers are 3-or-more digit numbers that meet one or more of the following criteria:
Any digit followed by all zeros: 100, ...
- 329
14
votes
21
answers
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views
Constructing Solar Panels from Squares
I'm designing a new space station for generic super-villain purposes (something something megalaser), but I'm having trouble designing the solar panels.
My genius team of scientists can calculate ...
- 11.1k
18
votes
15
answers
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views
Verb arities in J trains
Background
J has trains similar to APL's. Given a sequence of verbs (functions), three rightmost verbs are grouped to form a derived verb (a fork) recursively, until one or two verbs remain. If the ...
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16
votes
19
answers
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views
Find the k-th order summary of a number
Background
The summary of a non-negative integer \$n\$ is the concatenation of all digits that appear in \$n\$ in increasing order, with each digit being preceded by the number of times it appears in \...
- 6,449
1
vote
0
answers
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views
Make me equal to 24 [duplicate]
Based on this game.
Description :
Based on Wikipedia's description.
The 24 Game is an arithmetical card game in which the objective is to find a way to manipulate four integers so that the end result ...
- 329
14
votes
13
answers
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Find the smallest solution for this simple equation
Input
4 integers w, x, y, z from the range -999 to 999 inclusive where none of the values is 0.
Output
4 integers a, b, c, d so that aw + bx + cy + dz == 0 where none of the values is 0.
Restrictions
...
user7467
28
votes
48
answers
3k
views
Swap Two Values in a List
Introduction:
Although we have a lot of challenges where swapping two items in a list is a subtask, like Single swaps of an array; Swap to Sort an Array; \$n\$ swaps into a nop; etc., we don't have ...
- 103k
59
votes
47
answers
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views
Increment The Time
Every digital clock contains a small creature that has to advance the time every minute [citation needed]. Due to the popularty of digital clocks and the popularity of catching them in the wild, they ...
- 42.9k
10
votes
5
answers
575
views
Khinchin's constant bad estimate [closed]
Inspired by How to write down numbers having an infinity of decimals? Link 🇫🇷
Background
From Wikipedia: for almost all real numbers \$x\$, coefficients \$a_i\$ ...
- 1,599
6
votes
16
answers
811
views
Written Word Equation
Word equations, but not as you know it! Given a sentence which will include two numbers, numerically, and a spelt operator, in the order seen in the examples, your goal is to give the numerical answer
...
- 1,682
20
votes
18
answers
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Adaptive randomisation
Given a number \$n ≥ 2\$, a blackbox function \$f\$ that takes no arguments and returns a random integer in the range 0...n-1 inclusive, and a number \$m ≥ n\$, your challenge is to generate a random ...
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11
votes
32
answers
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Index and return 3 characters
The challenge is simple: Read 3 letters from a system input¹ and convert them to numbers (A-1, B-2, C-3...Z-26)². Print each of those numbers in the order the ...
- 261
4
votes
3
answers
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views
Will the hydra finally die? Part II
Background
This is a follow up question to the question: Will the Hydra finally die?
As before a dangerous A Medusa have released a dangerous Hydra which is revived unless the exact number of heads it ...
- 679
19
votes
10
answers
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Ploughed fields via moduli
Let \$R, C\$ be positive integers and let \$0 < s \leq 1\$. Consider the \$R \times C\$ matrix \$\mathbf M\$ defined as
\begin{equation}
M(i,j) = \frac{\mathrm{mod}\,(j, i^s)}{R^s}, \quad i = 1, \...
- 99.3k
15
votes
10
answers
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Project Euler 1: Multiples in constant time
The purpose of this challenge is to solve the original first Project Euler problem, but as the title suggests in constant time (with respect to the size of the interval).
Find the sum of all the ...
- 679
26
votes
13
answers
2k
views
Is it a Giuga number?
Giuga numbers (A007850) are composite numbers \$n\$ such that, for each prime factor \$p_i\$ of \$n\$, \$p_i \mid \left( \frac n {p_i} -1 \right)\$. That is, that for each prime factor \$p_i\$, you ...
- 46.7k
4
votes
9
answers
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Will the Hydra finally die?
Background
A Medusa have released a dangerous Hydra which is revived unless the exact number of heads it have is removed. The knights can remove a certain number of heads with each type of attack, and ...
- 679
21
votes
16
answers
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Largest Number with No Repeating Digit Pairs
Inspired by the problem with the same name on Puzzling SE by our very own Dmitry Kamenetsky.
You are to find the largest number that only uses every digit pair once, in a given base. For example, in ...
- 1,921
29
votes
33
answers
2k
views
Mr. Binary Counterman
Mr. Binary Counterman, son of Mr. Boolean Masker & Mrs. Even Oddify, follows in his parents’ footsteps and has a peculiar way of keeping track of the digits.
When given a list of booleans, he ...
- 1,921