Can't sleep. So here's last year's Advent of Code, day 1, in 3 lines of J.
Simple, right?
Alright, not so simple. I have annotated it in the second picture.
I'm sure you can do this even more tersely, but I'm very much a newbie to J.
Looking forward to trying it on this year's problems. 😄
Finally figured out how to write a sliding window function in J.
Code's now at https://gist.github.com/SamirTalwar/a0dddc670bda4a5cc757574bdeb5abde. I'm not uploading it to my main repo because it's not really set up to handle more than one language for the same year.
`$` is the "reshape" operator, which you can use to reshape an array.
`i. n` creates a range from 0 to n.
It works like this:
```
3 3 $ i. 9
0 1 2
3 4 5
6 7 8
```
There's gotta be a better way to create a column of numbers from 0 to n than `(n , 1) $ i. n`, but I can't find it.
Advent of Code 2021, day 2, in J.
I do not like this solution. It relies a lot on mutation and just pretending the input is J (`".` is basically `eval`).
I need to find a way to fold over my input better. Tried looking into state machines but it made my brain bleed. (https://www.jsoftware.com/help/dictionary/d332.htm)
If you need alt text, you're probably better off viewing the code at https://gist.github.com/SamirTalwar/a0dddc670bda4a5cc757574bdeb5abde.
I made my first J adverb! It takes a dyadic verb (a verb with two parameters, to its left and right), and makes the right parameter a list, which it folds over.
I feel very smug. Better go to bed before this gets out of hand.
Code here (AOC_02_2.ijs): https://gist.github.com/SamirTalwar/a0dddc670bda4a5cc757574bdeb5abde
Samir Talwar