Flatten from the inside out Say we have a ragged list [ [1, 2], [3, [4, 5] ], ] And we want to flatten it by a layer, decreasing its depth by 1. We could flatten it from the outside: [1, 2, 3, [4, 5]] Or, we could flatten it from the inside. To do this, take all subarrays with maxima...

Truncate words in a sentence Inspired by wezl. Your challenge is to take words (sequences of [a-zA-Z]) and truncate them to length 3. For example, never gonna give you up would become nev gon giv you up. Words will not necessarly be delimited by spaces - for example, youtube.com/watch?v=dQw4w9WgX...

Enumerate all pure sets open-ended-function In set theory, a set is an unordered group of unique elements. A pure set is either the empty set \$\{\}\$ or a set containing only pure sets, like \$\{\{\},\{\{\}\}\}\$. Your challenge is to create a bijection from positive integers to pure sets. This...

Is it a valid list? Given a string like [[[],[[]]],[]], made of only commas and square brackets, your challenge is to determine whether it represents a list. A list is either: [], the empty list At least one list, joined with commas and wrapped in square brackets. You may output as: Any two co...

This is a cross-post of a problem I posted to anarchy golf: http://golf.shinh.org/p.rb?tails Given two integers \$ n \$ and \$ k \$ \$ (0 \le k \le n) \$, count the number of combinations of \$ n \$ coin tosses with at least \$ k \$ tails in a row. For example, if \$ n = 3 \$ and \$ k = 2 \$, the...

Your goal is to print (to the standard output) the largest number possible, using just ten characters of code. You may use any features of your language, except built-in exponentiation functions. Similarly, you may not use scientific notation to enter a number. (Thus, no 9e+99.) The program m...

Some of my old questions, such as Paint Starry Night, objectively, in 1kB of code or Write Moby Dick, approximately have large numbers of really great answers and still occasionally get answers today. I used to use the leaderboard snippet to keep track of the scores, but I found today that it's n...