21 questions linked to/from Tips for golfing in APL
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### An abundance of integers!

An Abundant number is any number where the sum of its proper divisors is greater than the original number. For example, the proper divisors of 12 are: ...
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### Sum square difference

The sum of the squares of the first ten natural numbers is, $1^2 + 2^2 + \dots + 10^2 = 385$ The square of the sum of the first ten natural numbers is, $(1 + 2 + ... + 10)^2 = 55^2 = 3025$ ...
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### Add N numbers without using + or -

Given N integers, output the sum of those integers. Input You may take the integers in any reasonable format, including: stdin arguments an array or list Rules ...
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### Name the Aztec year

It's time for another Mesoamerican calendar! The Xiuhnelpilli was used by the Aztecs (more properly, the Mexica) to name their years. Each year has a number and a sign. Here's part of the cycle: <...
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### Tips for golfing in J

GolfScript gets its own way far too often and I feel that a repository of handy hints for golfing in J might help in the fight against the evil empire. What tips do you have for making this already ...
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### Bit delivery in Bin City

sandbox Story Similar to a newspaper route you have been tasked with delivering bits to the residents of Bin City. Just as certain people like certain newspapers, the citizens of Bin City prefer ...
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### Pendulum Encoding

Given a string as an input (which can be any acceptable/convenient format in your language), implement pendulum encoding. The test cases are split into individual items (which aren't quoted) for a ...
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### pleTriwapt Sgpin (Triplet Swapping)

Intro/Background I was looking at a Flybuys card at Coles recently and noticed that if I took something like this: Source, randomly found on the Internet And swapped some words around, I'd get ...
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### The SBEVE Challenge

She said s(he) be(lie)ve(d), he said sbeve. Input A non-empty string, s. It's guaranteed that s will have only printable ASCII ...
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### Rotation summation

Take a square matrix containing positive integers as input, and calculate the "rotated sum" of the matrix. Rotated sum: Take the sum of the original matrix and the same matrix rotated 90, 180 and ...
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### Generate input for this hardware

I have a hardware that has a 32-bit input register. The register has the following characteristics: The 32-bit register consists of eight 4-bit fields. Each 4-bit field holds a value in signed-...
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### Create an “H” from smaller “H”s

Challenge Create a function or program that, when given an integer size, does the following: If size is equal to 1, output ...
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### Print the sequence

21, 21, 23, 20, 5, 25, 31, 24, ? Inspired by this Puzzle, given an integer $n>0$ , print out the following sequence until you reach a non-Integer (spoilered, in case you want to solve the puzzle ...