Questions tagged [array]
A competition to solve a particular problem through the usage and manipulation of arrays.
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Calculate sum of self-exponentation
Given an array of positive integers, calculate the sum of each number raised to its own power. For example, given 4,6,7, the code needs to return \$4^4+6^6+7^7=...
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Generate a subgroup of a free group
In group theory, the free group with \$n\$ generators can be obtained by taking \$n\$ distinct symbols (let's call them \$a, b, c ...\$ etc), along with their inverses \$ a^{-1},b^{-1},c^{-1} ...\$ . ...
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Is it a cartesian product?
The cartesian product of two multisets \$A\$ and \$B\$ is the multiset of all ordered pairs consisting of an element of \$A\$ and an element of \$B\$. For example, the cartesian product of \$\{1, 2, 7,...
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Weave two lists, cycling if necessary
Consider two lists, A and B. To weave them together, we take the first element of A, then the first element of B, then the next element of A, the next element of B, and so on, ending with the last ...
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Emulate Jelly's tie-scan
The golfing language Jelly has a built-in ƭ called "tie", that cycles through a list of functions every time it's called. For example, ...
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Reconstruct a list of strings from its prefixes
emanresu A posted a challenge to reconstruct an ordered list of integers from its unordered set of unordered prefixes. Many users (beginning with xnor's answer) noticed that summing each unordered ...
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Reconstruct a list from its prefixes
A list \$[a_1,a_2,a_3 \cdots a_n]\$ can be uniquely represented as an unordered list of its prefixes - \$ [[a_1],[a_1, a_2], [a_1,a_2,a_3] \cdots [a_1,a_2,a_3 \cdots a_n]] \$. This can be in any order ...
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Contract a tensor
Introduction
Tensor contraction is an operation that can be performed on a tensor. It is a generalization of the idea of the trace of a matrix. For example, if we have a rank-2 tensor (a matrix) and ...
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Search the deepest depths of an array
Given a ragged array, find the length of the largest subarray that contains the depth of that subarray. The base array layer has a depth of 0.
Here is an example:
...
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Remove falsy rows and columns
Your challenge is to, given a matrix of nonnegative integers, remove all rows and columns that contain a 0.
For example, with this matrix:
...
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What and where is the max?
This small challenge derives from my annoyance at discovering that numpy doesn't have a built in function for it.
Input
An n by m matrix of integers.
Output
The maximum value in the matrix and the 2d ...
- 3,153
7
votes
4
answers
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Busy Letters & Evil CEOs
Imagine you are given an array/string containing \$5\$ letters of the English alphabet, with each letter having any value from A to Z (inclusive).
Every day, each letter will perform a job, which can ...
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"Perfect" an array
Given an n non-negative integers, how many numbers must be changed so that each number x appears x times? You cannot add or remove elements, only replace them with other numbers.
For example:
...
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Unnecessary Fluff
Following the great advice (what do you mean it's not advice?!) on Adding unnecessary fluff we can devise the following task:
Take a list of positive integers and a positive integer \$m\$ as input.
...
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Is it stuck in a counting loop? [duplicate]
Given a list of non-negative integers the function \$f\$ replaces every integer with the number of identical integers preceding it (not necessarily contiguously). So
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Night hike partitioning
We want to go on a night hike with the youth group, but of course not everyone has their torch, even though we told them we planned to split up. What options are there for group formation if n teens ...
- 2,660
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One-dimensional map colouring
It is a well-known fact that you can colour a two-dimensional map with four colours in such a way that two countries with a common border always have different colours. There have already been enough ...
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24
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Just another traffic jam!
One lane is closed, the vehicles have to thread their way in according to the zip-lock system: One car from one lane, the next car from the other lane, always taking turns.
Input: Two vehicle queues, ...
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votes
16
answers
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Which skill to train?
Story (skip, if you prefer the naked task): You need five skills for an imaginary sport: Speed, strength, endurance, accuracy and tactics. If you achieve a score in each of these disciplines, you can ...
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votes
2
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How many twisted corners?
Your challenge is to output the number of twisted corners given a 2x2 Rubik's Cube scramble.
For the purpose of this challenge, twisted corners are defined as corners where the colour of the top/...
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votes
9
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Seat gangs as far as possible
Imagine there are \$n\$ people \$\{a_1, a_2, \ldots, a_n\}\$ who enter a room in order and sit down in \$n\$ seats, arranged in a row. Each of these people belong to some gang, indicated by an integer ...
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How many umbrellas to cover the beach?
You work at a beach. In the afternoon, the sun gets quite hot and beachgoers want to be shaded. So you put out umbrellas. When you put out umbrellas you want to shade the entire beach, with as few ...
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Transpose a multidimensional array
Transposition is an operation on 2-dimensional arrays that flips every element across the main diagonal:
...
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votes
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Output the longest list
In this challenge you will take a non-empty (finite) list of (possibly infinite) lists of positive integers, and your task is to output the longest one. An infinite list is longer than a finite list ...
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Complement an infinite list
In this challenge, we define the complement of a list of positive integers as all positive integers not included in that list. For example, the complement of the even numbers ...
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vote
2
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Compute how many are no larger than each item in an array
Input: an array of length \$n\$ containing integers in the range \$0\$ to \$2n\$.
For each integer \$x\$ in the array, compute the number of integers that occur before \$x\$ that are no larger than \$...
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votes
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Reconstruct an array by successive insertions
Given an array of letters in the range 'a' to 'o', compute how to construct the array by successively inserting the letters in alphabetical order. You will always start the insertion with a base array ...
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votes
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Find the largest sum such that no two elements are touching
Inspired by this (off topic) post
Given an array of numbers, find the largest sum over a subarray not containing two adjacent elements
...
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What's my score?
The question score on Stack Exchange is the total number of upvotes minus the total number of downvotes a question receives. However, the reputation gained/lost for every upvote/downvote is different (...
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Longest Consecutive Sequence
Description
Given a list of positive integers, write the shortest code to find the number count of the longest consecutive sequence of numbers within the list.
Input
A list of positive integers. You ...
- 1,802
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answers
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DP approach gives TLE [closed]
There is a question to basically find the largest sum in an array, such that no two elements are chosen adjacent to each other. The concept is to recursively calculate the sum, while considering and ...
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Diagonalize a vector
Diagonalize a vector into a matrix.
Input
A vector, list, array, etc. of integers \$\mathbf{v}\$ of length \$n\$.
Output
A \$n \times n\$ matrix, 2D array, etc. \$A\$ such that for each element \$a_i \...
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votes
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answers
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Complete the landscape
Carcassonne is a tile-based game, where the objective is to construct Roads, Cities and Monasteries, in order to score points. The game works by players taking turns to draw and place tiles to ...
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Adjacent Items Sorting
Given a list, L, of sets of numbers like this:
[[1], [0,2,3], [3,1], [1,2,3]]
Output a single list of numbers such that 2 ...
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Compute cumulative means efficiently
Consider a sorted array of positive floating point numbers such as:
input = [0.22, 2.88, 6.35, 7.17, 9.15]
For each integer \$i\$ from 1 up to the last value in ...
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votes
6
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"Signpost" puzzle from Tatham's collection
Simplified version of "Signpost" puzzle from Simon Tatham's Portable Puzzle Collection.
How the puzzle is created
We pick up randomly positive integer N ...
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Counting fading
Background
Being in a philosophical mood, I remembered one old idea. I think it is suitable for CG.
Duplicates are not found, but it's of course just a kind of totalistic cellular automaton or erosion....
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35
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The Jaccard Index
The Jaccard index / similarity coefficient, also known as the Tanimoto index / coefficient, is a statistic used for gauging the similarity and diversity of finite sample sets. It was developed by ...
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Cosine similarity of two vectors
The cosine similarity of two vectors \$A\$ and \$B\$ is defined using their dot product and magnitude as:
\$\frac{A\cdot B}{\|A\|\|B\|}\$
Or in other terms
\$\frac{\sum_{i=1}^nA_iB_i}{\sqrt{\sum_{i=1}^...
- 1,807
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Make a Custom Bayer Matrix
A Bayer matrix is a threshold map used for ordered dithering that gives the illusion of having more shades of color than actually present by using a crosshatch-like pattern.
Bayer matrices are square ...
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votes
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Shortening this Code to process nested tuple even further without the use of max()
I have the code:
...
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How long to carry sort?
Carry sort is an \$O(n)\$ "sorting" algorithm. Here's how it works. The algorithm moves left to right along a list. As it traverses a list it "carries" a single item, the largest ...
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Is it a valid chemical?
Non-metals typically* have a fixed number of covalent bonds in every chemical they are part of. Given the number of bonds every element requires, output whether it's possible to construct a single ...
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Is it traversable?
Imagine that a list of integers describes the heights of some two-dimensional terrain as seen from the side.
Stamina: [ 4 4 4 4 4 4 3 3 3 3 2 2 2 - ]
O
...
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Guessing on straws
Dedicated to Martin Gardner, taken from his book
Background
In the old days, the Slavs had a divination method for finding out whether a girl would get married. The girl would clutch six straws in her ...
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Counting Letters in a String
Write a program or function that takes in a string and outputs a count of each modern English alphabet letter in the string, case-insensitive.
Input: A string consisting of printable ASCII characters (...
- 1,802
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votes
29
answers
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String with the smallest sum of ASCII values
Description
In this challenge, you need to write a function that takes in a list of strings and returns the smallest string based on their ASCII value. You should assume that the input list contains ...
- 1,802
10
votes
3
answers
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Voronoi-Lloyd ASCII art [closed]
Voronoi diagram is a partition of a plane (or part of plane) into regions close to each of a given set of objects ("seeds").
Here we’ll be dealing with discrete arrays or even rather with ...
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votes
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Shortest Code to Find the Smallest Missing Positive Integer
Description
Given an unsorted array of integers, find the smallest positive integer that does not appear in the array. Your task is to write the shortest code possible to solve this problem.
Input
A ...
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