Questions tagged [array]

A competition to solve a particular problem through the usage and manipulation of arrays.

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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, ...
Philippos's user avatar
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15 votes
14 answers
3k views

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 ...
Philippos's user avatar
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7 votes
2 answers
303 views

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/...
math scat's user avatar
  • 8,463
14 votes
9 answers
2k views

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 ...
97.100.97.109's user avatar
30 votes
20 answers
4k views

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 ...
Wheat Wizard's user avatar
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16 votes
9 answers
1k views

Transpose a multidimensional array

Transposition is an operation on 2-dimensional arrays that flips every element across the main diagonal: ...
emanresu A's user avatar
  • 35.6k
3 votes
7 answers
796 views

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 ...
Wheat Wizard's user avatar
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18 votes
20 answers
2k views

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 ...
emanresu A's user avatar
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1 vote
2 answers
544 views

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 \$...
Simd's user avatar
  • 1,812
17 votes
17 answers
2k views

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 ...
Simd's user avatar
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23 votes
23 answers
2k views

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 ...
bsoelch's user avatar
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16 votes
6 answers
2k views

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 (...
math scat's user avatar
  • 8,463
24 votes
28 answers
3k views

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 ...
Aitzaz Imtiaz's user avatar
1 vote
0 answers
189 views

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 ...
BlazeRod11's user avatar
24 votes
38 answers
2k views

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 \...
bigyihsuan's user avatar
  • 8,538
17 votes
4 answers
650 views

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 ...
caird coinheringaahin g's user avatar
13 votes
10 answers
1k views

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 ...
mousetail's user avatar
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12 votes
17 answers
2k views

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 ...
Simd's user avatar
  • 1,812
16 votes
6 answers
896 views

"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 ...
lesobrod's user avatar
  • 3,239
24 votes
17 answers
1k views

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....
lesobrod's user avatar
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17 votes
35 answers
2k views

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 ...
solid.py's user avatar
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21 votes
29 answers
2k views

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}^...
emirps's user avatar
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14 votes
13 answers
1k views

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 ...
Yousername's user avatar
  • 3,650
5 votes
2 answers
373 views

Shortening this Code to process nested tuple even further without the use of max()

I have the code: ...
Dark Programmer's user avatar
15 votes
17 answers
2k views

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 ...
Wheat Wizard's user avatar
  • 96.5k
29 votes
13 answers
3k views

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 ...
mousetail's user avatar
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29 votes
17 answers
3k views

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 ...
chunes's user avatar
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13 votes
7 answers
762 views

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 ...
lesobrod's user avatar
  • 3,239
11 votes
41 answers
2k views

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 (...
Aitzaz Imtiaz's user avatar
5 votes
25 answers
520 views

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 ...
Aitzaz Imtiaz's user avatar
10 votes
3 answers
611 views

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 ...
lesobrod's user avatar
  • 3,239
27 votes
52 answers
3k views

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 ...
Aitzaz Imtiaz's user avatar
12 votes
6 answers
609 views

Number Clusters

Your task is to create a program or function, that when given an input list of nonnegative integers of length \$l \ge 2\$ and a nonnegative integer \$c\$ where \$2 \le c \le l\$, group the list into \$...
Yousername's user avatar
  • 3,650
7 votes
18 answers
605 views

Find the largest sum of any contiguous subarray of the array [duplicate]

Let's say you are given an integer array. Create a function to determine the largest sum of any array's adjacent subarrays. For instance, the contiguous subarray with the largest sum is ...
user avatar
11 votes
26 answers
2k views

Arbitrary Apple Dilemma

I have encountered this type of puzzle, that usually involves apples, several times. It goes as follows: There is a certain number of apples in a basket. Ava takes a third of the apples. Bob takes a ...
math scat's user avatar
  • 8,463
14 votes
8 answers
1k views

Change the subject

Sometimes I feel like the conversation is going down the wrong path and take it upon myself to steer it in another direction. And this conversation is going wrong real fast, so I need to change the ...
noodle man's user avatar
  • 5,212
17 votes
16 answers
730 views

Form a subset that is a continuous range

Given a list of lists of positive integers, output a subset of them so their union forms a continuous non-empty range with no numbers missing. For example, consider this input: ...
mousetail's user avatar
  • 11.8k
13 votes
17 answers
2k views

Remove duplicates from my academic transcript

Consider a list of subject, grade pairs. E.g. ...
Simd's user avatar
  • 1,812
8 votes
32 answers
1k views

Keep elements in sequence that have a letter repeated at least 3 times

Challenge: Given the input array l with a list of strings, only keep the elements in the sequence that have a letter that's repeated at least 3 times. Like ...
U13-Forward's user avatar
  • 2,001
13 votes
35 answers
735 views

Create \$n\$ sublists with the powers of two (1, 2, 4, 8, 16...)

Challenge: Given the input number n. It should give me nested sublists of n layers with the power of two numbers for each level. ...
U13-Forward's user avatar
  • 2,001
18 votes
22 answers
865 views

Generate recursive "arrays" up to a certain depth

Given a positive integer n. Generate a JSON array (can be a string, or your language's built-in JSON representation as long as we can get valid JSON, (your code ...
f478ccf2's user avatar
  • 183
13 votes
10 answers
659 views

CGAC2022 Day 8: Fen The Wicked, Part 2

Part of Code Golf Advent Calendar 2022 event. See the linked meta post for details. Fen is a magician Elf. He can cast spells on an array of numbers to produce another number or array of numbers. One ...
Bubbler's user avatar
  • 73.8k
20 votes
25 answers
1k views

CGAC2022 Day 7: Fen The Wicked

Part of Code Golf Advent Calendar 2022 event. See the linked meta post for details. Fen is a magician Elf. He can cast spells on an array of numbers to produce another number or array of numbers. One ...
Bubbler's user avatar
  • 73.8k
11 votes
6 answers
435 views

Conversions Galore!

Imagine that there are \$n\$ different types of objects \$O_1,O_2,O_3,\ldots,O_n\$ and they each have a conversion factor \$k_1,k_2,k_3,\ldots,k_n\$. You can, for any \$1\le i\le n\$, convert \$k_i\$ ...
Aiden Chow's user avatar
  • 12.7k
6 votes
5 answers
897 views

What is the longest trampoline?

In this challenge we are going to consider lists of integers such that for every member \$x\$ at index \$i\$ then the indexes \$i+x\$ and \$i-x\$ have the value \$x+1\$ or are out of bounds for the ...
Wheat Wizard's user avatar
  • 96.5k
22 votes
15 answers
2k views

Construct a diverse array

Given an integer \$ n \ge 1 \$, your task is to output an array \$ a \$ consisting of \$ n^2 + 1 \$ integers, such that all possible pairs of integers \$ (x, y) \$ satisfying \$ 1 \le x, y \le n \$ ...
dingledooper's user avatar
  • 22.3k
17 votes
9 answers
1k views

Longest alternating subsequence

inspired by Longest Increasing Substring Task Given a list of non-negative integers, output the length of its longest alternating subsequence. An alternating sequence is a sequence of numbers which ...
Bubbler's user avatar
  • 73.8k
23 votes
45 answers
2k views

Repeat Values In Array

Given two arrays of non-negative integers \$A = [A_1,A_2,\ldots,A_n]\$ and \$R = [R_1,R_2,\ldots,R_n]\$ which are equal in length, return an array which has the element \$A_1\$ repeated \$R_1\$ times, ...
97.100.97.109's user avatar
24 votes
16 answers
2k views

Reconstruct Matrix from its diagonals

Given the diagonals of a matrix, reconstruct the original matrix. The diagonals parallel to the major diagonal (the main diagonals) will be given. Diagonals: ...
math scat's user avatar
  • 8,463
10 votes
1 answer
519 views

Optimally pop all the bubbles

In a given 2d grid of positive integers (representing different types of "bubbles"), there are one of two actions that you can do each "step". You can either: Pop an island (a ...
Aiden Chow's user avatar
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