What feels like a million years and a lifetime ago, I wrote up a library for perlin and simple noise in Racket. Inspired by Jens Axel Søgaard’s new Sketching library (processing in Racket) and a conversation thereabout, I figure it’s about time to push noise to the raco package manager!
I recently came across a question: how do you read extended file attributes in Racket. Not being actually that familiar with extended file attributes, I searched online. Nothing seems to currently exist (other than in the FUSE module, but that’s specific to FUSE), but there is a system level exectuable that one could wrap to do this. I haven’t done much1 with Racket’s system
or system*
function before, so let’s give it a whirl.
Part 1: Create an infinite stream of numbers, by starting with [3, 7] with two pointers: 0 and 1. To add values to the list:
- Add the current values of the two pointers
- If the value is less than ten, add that value to the end of the list
- If the value is greater or equal to ten, add 1 and then the ones digits to the end of the list
- Update each pointer by adding the value it is pointing at to its current index plus one
With that algorithm, find the ten digits after a given index.
Part 1: Load a minecart track that looks like this:
/->-\
| | /—-
| /-+–+-\ |
| | | | v |
-+-/ -+–/
-—–/
Part 1: Create an infinite 2D cellular automaton with transition rules based on two points to each side, starting with initial state at index 0 to the right.
After 20 generations, what is the sum of indexes of points turned on?
Part 1: Define a grid as follows (x,y coordinates + a constant C):
- r(x) = x + 10
- G(x, y) = hundreds(r(x) * (r(x) * y + C)) - 5
Find the 3x3 area in a 300x300 grid with the highest total G(x, y) .
Part 1: Given a system of moving particles (with position and velocity) find the point where the particles spell a message. What is that message?
Part 1: Place marbles in a circle such that each marble is placed by skipping one place except for marbles divisible by 23. For those, don’t place them, skip back 7 places, and remove that marble as well. Add these two marbles to your current score.
Given a specific player count and last marble, what’s the highest score?
Part 1: A custom tree data structure is defined as:
- child count
- metadata count
child countadditional subtrees (recursive)metadata countmetadata nodes
Calculate the sum of all metadata nodes.
Part 1: Given a list of job dependencies (job A must be before job B), determine the order jobs must be done in. Break ties lexicographically.