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Questions tagged [repeated-transformation]

The puzzle or challenge involves repeated application of some transformation to the input. These puzzles often involve mathematical sequences or fractals.

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47answers
4k views

Multiplicative persistence

Multiplicative Persistence Multiply all the digits in a number Repeat until you have a single digit left As explained by Numberphile: Numberphile "What's special about 277777788888899?" Numberphile ...
9
votes
5answers
640 views

Abstract Rewriting Challenge (Robbers)

This is a somewhat proof-golf-like cops-and-robbers challenge. This is the robbers' thread; the cops' thread is here. Robbers The cops will post abstract rewriting systems. Your task is to crack ...
26
votes
10answers
945 views

Abstract Rewriting Challenge (Cops)

This is a somewhat proof-golf-like cops-and-robbers challenge. This is the cops' thread; the robbers' thread is here. Cops Your task is to define an abstract rewriting system in which the ...
15
votes
8answers
823 views

Create an omnifix calculator

Inspiration. Inverse. Evaluate a given omnifix expression. Omnifix is like normal mathematics' infix notation, but with additional copies of each symbol surrounding the arguments. The outer symbols ...
21
votes
8answers
2k views

Arnold's Cat Map

Challenge Given a colour raster image* with the same width and height, output the image transformed under Arnold's cat map. (*details see below) Definition Given the size of the image ...
12
votes
1answer
326 views

Prove 2+2=2*2 (and similar)

Output a full formal poof of such statements such as 1+2=3, 2+2=2*(1+1) etc. Introuction If you know Peano Arithmetic you can ...
9
votes
1answer
265 views

Flexagonal flexagation

Being programmers, watching us flex aren't very interesting. Today we change that! In this challenge you will lex and flex hexaflexagons. About For a video introduction, watch viharts video(s) on ...
44
votes
26answers
6k views

How does math work in Anastasiya's world?

Background: Standard operation math like basic addition and multiplication in the real world work like these: 12 + 123 = 135 and ...
22
votes
4answers
762 views

Optimizing SKI compiler

The SKI calculus is a variant of the Lambda calculus that doesn't use lambda expressions. Instead, only application and the combinators S, K, and I are used. In this challenge, your task is to ...
2
votes
2answers
229 views

Looping Random Number Generator [closed]

I'm not even sure if this is even possible, but I think it's worth a shot. The Challenge Code/conceptualize a pseudo-random number generator that has the potential to produce results evenly spaced ...
4
votes
3answers
3k views

Generate unique non-sequential string of length n without memory of previously generated strings

Scenario: Imagine a situation where you wish to share a unique alphanumeric code. Perhaps it is a one-time-use coupon code you hand write on business cards, or some other scenario where it is ...
24
votes
22answers
4k views

Code Golf: 6174 - Kaprekar's mythical constant

Why is the number 6174 so interesting? As defined by Wikipedia Take any four-digit number, using at least two different digits. (Leading zeros are allowed.) Arrange the digits in ascending ...
20
votes
28answers
4k views

Additive Persistence

The shortest code to pass all possibilities wins. In mathematics, the persistence of a number measures how many times a certain operation must be applied to its digits until some certain fixed ...
12
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12answers
2k views

Hitting 495 (Kaprekar) [duplicate]

Input: A three digit number from stdin or as an argument not all digits are the same may start with one or two zero's Process Order the input-digits ascending and descending to form two new ...
14
votes
20answers
1k views

Random dice tipping

In a standard dice (die) the numbers are arranged so that opposite faces add to seven. Write the shortest possible program in your preferred language which outputs a random throw followed by 9 random ...