Questions tagged [integer]

For challenges involving the manipulation of integers.

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64
votes
52answers
6k views

N-dimensional N^N array filled with N

In: Enough memory and a positive integer N Out: N-dimensional N^N array filled with N, where N^N means N terms of N-by-N-by-N-by... Examples: 1: [1] ...
33
votes
43answers
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 ...
17
votes
105answers
7k views

Turn an integer n into a list containing it n times [closed]

Given an integer n as input, return a list containing n, repeated n times. For example, the ...
23
votes
47answers
5k views

Sort an Integer List

The Challenge It's quite simple really, sort a list of numbers. Details You must sort a list of numbers in ascending order, without using any built-in sorting functions/libraries/etc (i.e. ...
62
votes
150answers
9k views

Print all integers

Write a program or function which will provably print all integers exactly once given infinite time and memory. Possible outputs could be: ...
81
votes
175answers
8k 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 ...
25
votes
25answers
2k views

Mountain range numbers

Mountain range number A number is a mountain range number if the inequalities satisfied by their consecutive digits alternate. In a way, looking at the number's digits should exhibit a ...
28
votes
69answers
9k views

Check whether an integer is a power of 2 without using +,- operations [closed]

Write a program that checks if the integer is a power of 2. Sample input: 8 Sample output: Yes Sample input: ...
23
votes
39answers
4k views

Smallest palindrome divisible by the input

Given a positive integer N, output the smallest positive integer such that this number is a palindrome (i.e. is its own reverse) and is divisible by ...
22
votes
12answers
2k views

Polynomialception

Given two polynomials f,g of arbitrary degree over the integers, your program/function should evaluate the first polynomial in the second polynomial. ...
34
votes
63answers
5k views

Find the highest unique digit

Surprisingly we haven't had a simple "find the highest digit" challenge yet, but I think that's a little too trivial. Given input of a non-negative integer, return the highest unique (ie not ...
25
votes
15answers
2k views

All the single eights

Given a non-empty rectangular array of integers from 0 to 9, output the amount of cells that are ...
24
votes
9answers
932 views

Spiral neighbourhoods

If we take the natural numbers and roll them up counter clock-wise into a spiral we end up with the following infinite spiral: ...
37
votes
50answers
3k views

(RGS 1/5) Binary multiples

A binary multiple of a positive integer k is a positive integer n such that n is written ...
11
votes
8answers
581 views

Bijective mapping from integers to a variable number of bits

A variable number of bits is an array of 0 or more bits. So [0, 1] is a variable number of bits, but so is []. Write a function ...
29
votes
36answers
3k views

Find the unique twins

You will be given two Arrays / Lists / Vectors of non-negative integers A and B. Your task is to output the highest integer N that appears in both A and B, and is also unique in both A and B. You ...
26
votes
68answers
5k views

How long is my number?

Challenge Given an integer \$Q\$ in the range \$-2^{100} ≤ Q ≤ 2^{100}\$, output the number of digits in that number (in base 10). Rules Yes, you may take the number as a string and find its length. ...
26
votes
11answers
5k views

Is this number an exact power of -2: (Very) Hard Mode

This is a version of the recent challenge Is this number an integer power of -2? with a different set of criteria designed to highlight the interesting nature of the problem and make the challenge ...
48
votes
32answers
2k views

Divisor skyline

For any positive integer \$k\$, let \$d(k)\$ denote the number of divisors of \$k\$. For example, \$d(6)\$ is \$4\$, because \$6\$ has \$4\$ divisors (namely \$1, 2, 3, 6\$). Given a positive integer \...
47
votes
52answers
7k views

Is this number an integer power of -2?

There are clever ways of determining whether a number is a power of 2. That's no longer an interesting problem, so let's determine whether a given integer is an integer power of -2. For example: <...
41
votes
29answers
4k views

Cops: The Hidden OEIS Substring

This is a Cops and Robbers challenge. This is the cop's thread. The robber's thread is here. As a cop, you must pick any sequence from the OEIS, and write a program p that prints the first integer ...
28
votes
8answers
2k views

Find number of ones to get a number using + and *

Introduction Your goal is to find the least number of ones you need to add or multiply together to get the input value, this is A005245. Input One positive integer N. Output The smallest number ...
15
votes
8answers
1k views

Summation under Zeckendorf Representation

Zeckendorf's theorem shows that every positive integer can be uniquely represented as a sum of non-adjacent Fibonacci numbers. In this challenge, you have to compute the sum of two numbers in ...
47
votes
142answers
9k views

Stay away from zero

Task Given a non-negative integer n, output 1 if n is 0,...
53
votes
43answers
3k views

Illustrate the Least Common Multiple

Given two positive integers, \$A\$ and \$B\$, illustrate their least common multiple by outputting two lines of dashes (-) with length \$\text{lcm}\$\$(A, B)\$ ...
45
votes
53answers
3k views

Output integers in negative order, increase the maximum integer everytime

Main task Your task is to print out integers in descending order, starting from 1, and increasing as you keep hitting 1 again, up until the given input is reached, then, print out the rest until you ...
42
votes
43answers
3k views

An Array of Challenges #1: Alternating Arrays

Alternating Arrays An alternating array is a list of any length in which two (not necessarily different) values are alternating. That is to say, all even-indexed items are equal, and all odd-indexed ...
34
votes
35answers
4k views

Is it a Mersenne Prime?

A number is a Mersenne Prime if it is both prime and can be written in the form 2n-1, where n is a positive integer. Your task is to, given any positive integer, determine whether or not it is a ...
30
votes
47answers
4k views

Which Card is it?

Introduction Long ago, when I used to code card games with usual playing cards, I used to specify a number for each card and call a function with some number to get a card. This somewhat inspired me ...
37
votes
26answers
5k views

Oddly Even, Positively Negative

Given N, output the Nth term of this infinite sequence: -1 2 -2 1 -3 4 -4 3 -5 6 -6 5 -7 8 -8 7 -9 10 -10 9 -11 12 -12 11 ... etc. N may be 0-indexed or 1-...
36
votes
59answers
6k views

Is my barcode valid?

An EAN-8 barcode includes 7 digits of information and an 8th checksum digit. The checksum is calculated by multiplying the digits by 3 and 1 alternately, adding the results, and subtracting from the ...
34
votes
4answers
4k views

The happy Ender problem

The happy ending problem (actually a theorem) states that Any set of five points in the plane in general position has a subset of four points that form the vertices of a convex quadrilateral. The ...
32
votes
33answers
2k views

Digits in their lanes

Input: A list of integers Output: Put each digit (and the minus sign) in its own lane, in the order -0123456789, ignoring any duplicated digits. Example: Input:...
21
votes
48answers
2k views

Find the sum of the divisors of N

Write a program that displays on the screen the sum of the divisors of a number (1 ≤ N ≤ 100) entered by the user in the range of 1 to N. This is OEIS A000203. Examples: Input: 7 ...
19
votes
29answers
1k views

Inverse Deltas of an Array

Your task is to, given an array of signed 32 bit integers, recompile it with its inverse deltas. For example, the list 1 3 4 2 8 holds the deltas: ...
15
votes
16answers
2k views

Computing a specific coefficient in a product of polynomials

Generator functions This gives the context for why this challenge came to life. Feel free to ignore. Generator functions are a nice way of encoding the solution to a problem of combinatorics. You ...
12
votes
13answers
2k views

Skip like a frog!

Given an array of non-negative integers, your task is to only keep certain elements of it, as described below. Let's say the array is ...
24
votes
3answers
2k views

The Path Of The Wildebeest

Golf a program or function which gives the \$n^{\text{th}}\$ location of the wildebeest who starts at square \$1\$ on an infinite chessboard which is numbered in an anti-clockwise square spiral, where ...
22
votes
18answers
1k views

Interpret Interval Notation

Interval notation is a way to write complicated range bounds more conveniently and concisely than writing an inequality. The challenge, should you choose to accept it, is to write a program or ...
16
votes
8answers
1k views

Decompose a number into triangles

Given an integer n, decompose it into a sum of maximal triangular numbers (where Tm represents the mth triangular number, or the sum of the integers from 1 to m) as follows: while n > 0, find the ...
2
votes
7answers
207 views

Bijective mapping from integers to a variable number of trits

This challenge is a harder version of this one. A variable number of trits is an array of 0 or more trits (a trit is a ternary digit). So [0, 2, 2, 1] is a ...
107
votes
35answers
12k views

What are the five most powerful characters in your language?

Choose any five characters your language supports. There are 5! = 5×4×3×2×1 = 120 ways these can be arranged into a 5-character string that contains each character once; 120 permutations. Choose your ...
35
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 ...
37
votes
80answers
4k views

Output the missing integer

You will be given a string. It will contain 9 unique integers from 0-9. You must return the missing integer. The string will look like this: ...
33
votes
4answers
3k views

Make The Finest Magic Code Square

In math a magic square is an N×N grid of numbers from 1 to N2 such that every row, column, and diagonal sums to the same total. For example here's a 3×3 magic square: In this challenge we'...
29
votes
46answers
5k views

How many petals around the rose

How many petals around the rose How many petals around the rose is a dice game you can play with your friends. Similar to "can I join the music box", there is a person that knows how the ...
28
votes
16answers
2k views

Output the Euler Numbers

Given a non-negative integer \$n ,\$ output the \$n^{\text{th}}\$ Euler number (OEIS A122045). All odd-indexed Euler numbers are \$0 .\$ The even-indexed Euler numbers can be computed with the ...
23
votes
22answers
2k views

Frequency Distribution of Multiple Dice Rolls

Given two positive integers a and b, output the frequency distribution of rolling a b-sided ...
22
votes
17answers
3k views

Make a Rectangle from a Triangle

You can depict a triangular number, T(N), by writing one 1 on a line, then two 2's on the line below, then three 3's on the line below that, and so on until N N's. You end up with a triangle of T(N) ...
19
votes
17answers
2k views

Find Integral Roots of A Polynomial

Challenge The challenge is to write a program that takes the coefficients of any n-degree polynomial equation as input and returns the integral values of x for which the equation holds true. The ...