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

learn more… | top users | synonyms

6
votes
5answers
262 views

Ordering an array of negatives, zero and positives integers with one iteration

Take an array of integers containing negative numbers, positive numbers and zeros. Group it with one iteration and in place such that all of the negative numbers come first, followed by all of the ...
36
votes
14answers
5k views

Into how many pieces can you cut this string?

Consider a piece of string (as in "rope", not as in "a bunch of characters"), which is folded back and forth on the real line. We can describe the shape of the string with a list of points it passes ...
11
votes
1answer
317 views

Score a game of Kingdom Builder

I want to try a new form of code golf here. Similar to bonuses, not all parts of the challenge have to be completed, but each answer has to implement a subset of certain size (and there is a core that ...
19
votes
10answers
835 views

0-1 Maximal Phase Counter

Consider an array of bits, say 1 1 1 0 0 0 0 1 0 0 1 0 1 1 1 1 1 0 1 0 We call a contiguous subarray of length ≥ 5 a phase if at least 85% of the bits are the same and the first/last bits are both ...
4
votes
2answers
169 views

Compute the Join and Meet of Partitions

Background In this challenge, a partition of a set S means a collection of nonempty subsets of S, which are mutually disjoint and whose union is S. We say that a partition p is finer than another ...
14
votes
8answers
866 views

Jump the Array!

Let's play a one-player game called jump the array. To play, you only need an array of integers, say a. You start at some position i, and on each turn, you jump to a new position. On turn n, if n is ...
28
votes
18answers
2k views

Unflatten an Array

This challenge was inspired by a question on Mathematica.SE. Say you've got a nested list/array of some arbitrary structure (the lists at each level don't necessarily have the same length). For ...
17
votes
6answers
1k views

Time Travelling Stock Trader

Story Long time ago Bobby created a Bitcoin wallet with 1 Satoshi (1e-8 BTC, smallest currency unit) and forgot about it. Like many others he later though "Damn, if only I invested more back then...". ...
32
votes
28answers
2k views

At least h with at least h

Input A list of nonnegative integers. Output The largest nonnegative integer h such that at least h of the numbers in the list are greater than or equal to h. Test Cases [0,0,0,0] -> 0 ...
13
votes
24answers
2k views

Shorter than a Split Second!

Challenge You task for this question is to split an input array of integers on the second occurrence of every integer in that array. Not clear enough ? Here is an example to help Input array: [2 1 ...
18
votes
37answers
2k views

Create an array with repeated numbers

Challenge Your task in this question is to write a program or a named function which takes a positive integer n (greater than 0) as input via STDIN, ARGV or function arguments and outputs an array ...
16
votes
24answers
3k views

Most common number

Calculate the most common number in a list. You should use an expression that fits on one line (the record is just 18 characters). d = [4,3,1,0,6,1,6,4,4,0,3,1,7,7,3,4,1,1,2,8] winner = ... # TODO: ...
3
votes
2answers
348 views

Shortest Code to Translate a PHP array

NOTE: This question was migrated from http://stackoverflow.com/q/27134588/1442685 PHP QUESTION Almost purely out of curiousity, how can I take an array like this: array( 'fruit' => 'banana', ...
5
votes
4answers
554 views

Shortest program to split special array

Background Imagine, you have a big array A, which is mostly zeroes, but contains a short subarray B which has only strictly positive entries. For instance: | A | [0 0 0 ...
17
votes
3answers
802 views

Book Stack Sort

When stacking books you usually want to put the largest ones at the bottom and the smallest ones at the top. However, my latent OCD makes me feel very uneasy if I've got two books where one is shorter ...
0
votes
2answers
88 views

Approximated (unsorted) square from a set of values [closed]

So a colleaque came with this problem lately and I want to challange you to solve the problem in the code-golf style, shortest solution in any language wins. The Problem: Given is a random set of ...
-2
votes
7answers
161 views

Create an array of unique ints in a set range

Goal: Write a piece of code that produces a array containing all integer values in a set range in random order (upper and lower bounds included). Use any language you like, but use as little built-in ...
8
votes
1answer
213 views

Golfscript Diagonal Array

Is there a way in Golfscript to bring all of the diagonals of an array into a single array? For example, for the array [[1 2 3][4 5 6][7 8 9]] return [[7][4 8][1 5 9][2 6][3]] (not necessarily ...
20
votes
32answers
3k views

Generating a single string with an Oxford comma from a list

What are some clever (brief and idiomatic) approaches to taking a list of strings and returning a single properly punctuated string built from the list, with each element quoted. This came up for me ...
2
votes
6answers
372 views

Programming Praxis - Survive like Flavius Josephus [duplicate]

Here's a challenge inspired by Programming Praxis: http://programmingpraxis.com/2009/02/19/flavius-josephus/ Write a function josephus(n,m) that returns a list of n people, numbered from 0 to ...
7
votes
15answers
692 views

Rank a list of scores with “skips”

Given a list of scores (non-negative integers) pre-sorted from greatest to least: [ 10, 10, 6, 6, 4, 0] Assign each score an integer rank, beginning with 1 and ascending, such that equal scores ...
1
vote
4answers
1k views

Rotate 2D Array [duplicate]

Given an input of a 2 dimensional array of integers, rotate the array 90 degrees clockwise. It should work for rectangular arrays of all sizes and proportions. The rotated array should be printed at ...
3
votes
2answers
393 views

Deplane! Deplane! (Or: RGBRGBRGB => RRRGGGBBB?)

Imagine bytes in memory for an RGB image--R and G and B represented by bytes in sequence. If an image is NxM then the memory layout will be M repetitions for vertical scanlines of 3*N bytes in ...
12
votes
5answers
530 views

Stack the deck!

Alice and Bob like to play a card game, with a deck of cards numbered with consecutive nonnegative integers. Alice has a very particular way of shuffling the deck, though. First, she takes the top ...
5
votes
22answers
2k views

Rotate An Integer Array with an O(n) algorithm

Write a function that rotates an integer array by a given number k. k elements from the end should move to the beginning of array, and all other elements should move to right to make the space. The ...
4
votes
5answers
397 views

How many times is rectangular array A embedded in rectangular array B?

Given two rectangular arrays, A and B, let's say that A is embedded in B if A can be obtained from B by deleting some (or none) of the rows and columns of B. Write a program with the following I/O: ...
3
votes
1answer
386 views

Change the innermost element type of a jagged array — any .NET language: C#, F#, VB.NET, MSIL, C++/CLI, etc

Write a class containing a method with the signature System.Array ChangeElementType(System.Array jaggedArray) (you may rename identifiers ChangeElementType, jaggedArray and shorten the type ...
1
vote
10answers
2k views

Convert JSON string to Key / Value Arrays

Convert JSON (key/value pairs) to a native arrays of keys & values, in your language. var X = '{"a":"a","b":"b","c":"c","d":"d","e":"e","f":"f9","g":"g2","h":"h1"}'; The value array could be ...
16
votes
15answers
2k views

Javascript: Create a 10x10 array of 1s

Obviously this challenge would be trivial with separate functions and libraries, so they aren't allowed. Your code must conform to an ECMAscript specification (any spec will do), so no ...
-2
votes
1answer
235 views

Merge working time periods

You have an array of working time period pairs (from, till) received from user input and written according 24-hour clock format convention. You have to merge these periods if the intersect each ...
7
votes
8answers
661 views

Array Sandwiches

(Adapted from Problem C of the first qualifier of the ACM Programming Contest of 2012/2013) You have several arrays, named A1, A2, ... , An, each sorted in ascending order. Every item in the array ...
4
votes
13answers
429 views

Create a hash from an array of arrays of key|value pairs

Starting from an array of sub-arrays, each sub-array is a 2 elements key|value pair. Example input = [["A", 5], ["B", 2], ["A", 12], ["B", -2], ["C", 7]] Convert this into a hash that has distinct ...
3
votes
5answers
251 views

Operations with Lists

Inspired by this question. Given a list containing numbers, print: The sum and product of the numbers in the list The average and median The differences between each term in the list (e.x. [1,2,3] ...
0
votes
1answer
186 views

Reduce the amount of loops when finding if an element is stored only once in the array? [closed]

I was amazed to find that there is a way to reduce the times you loop on an array to find if a element is contained once. One would think that the only way would be to loop through the whole array, ...
2
votes
3answers
359 views

Polynomial extrapolation

Task Given a list of integers a1, a2, …, ak (k ≥ 2) and a positive integer m, write a function or a complete program that calculates the next m numbers of the list. Assume that ai = P(i) ...
10
votes
15answers
2k views

Shuffle a deck without local variables

The object of this puzzle is to take a deck of 52 cards and shuffle it so that each card is in a random position. Given: An array, deck, of 52 distinct integers representing the cards. When you ...