Advent of Code 2015 days 3-8 in Clojure

Yeah, I'm starting to think my initial comment about taking until the heat death of the universe to complete this wasn't far off the mark. I'm not really slow at finishing the tasks, it's just between working , the drudgery of everything else in life and possible undiagnosed ADHD, progress becomes a sporadic thing. Gone forever I think are the late-nighters of chugging caffeinated drinks...

But with that said, I have been slowly chugging away and gotten myself up to the heady heights of puzzle number 8.

I don't think I shall labour over each and every puzzle, instead I'll just gloss over the interesting parts.

Day 03

You're trying to determine how many points are visited if you're given a list of directions (N/S/E/W effectively). One pattern with this sort of thing I like to do is to store the position transformation as a map with the keys being the direction and the values being values to add to x and y coordinates.

(def moves {\^ [0  1]
            \v [0 -1]
            \> [1  0]
            \< [-1 0]})

The rest is just bookkeeping ;D

Day 04

Trying to mine a proprietary cryptocoin. I just used Java interop here - (java.security.MessageDigest/getInstance "MD5"). It is then a matter of looping through numbers to get the required number of leading zeros in the hexadecimal representation of the digest.

This was pretty brute-force and I don't expect to retire from crypto riches any time soon. It's quite slow too - clearly the hashing is going to be but I suspect we could possibly run multiple threads in parallel and/or optimise the way we're creating the byte-array to feed into Java each loop.

As it is, I was content just to wait for it to finish...

Day 05

String parsing really. I'm not a massive fan!

Was nice going back to see part of my original solution looks like this;

(defn nice?
  "is a word nice?"
  [word]
  (and (has-three-vowels? word)
       (has-repeated-letter? word)
       (no-forbidden-strings? word)))

Pretty legible. I guess you'd write something similar in most languages, but the convention of adding a question mark to tests is a nice touch.

Day 06

Mapping text instructions into turning a series of lights on/off/toggling in a given rectangle. Nothing to write about but I was interested to see if anyone had plotted the result in case there was a picture.

There isn't.

Day 07

Ah, we're getting interesting now, we had to simulate a basic logic circuit. We're given a input like;

123 -> x
456 -> y
x AND y -> d
x OR y -> e
x LSHIFT 2 -> f
y RSHIFT 2 -> g
NOT x -> h
NOT y -> i

I suspect there's a proper way of doing this in which we create a graph of connections and evaluate everything in the proper order. But what I did was just to brute force the whole thing; just keep running through the instructions until every instruction could be executed e.g. if you imagine in the example above that the numbers aren't applied to x and y until the last line, then we couldn't perform most of it until the second loop round the instructions.

Yes, as I edit this, I'm seeing a theme forming here where my solutions are just brute forced.

Day 08

String parsing again :D Trying to count the number of characters in a string and in the final representation. Not much to say again. Slogged through it.

Parser?

So far each problem's input is basic text, but I'd be interested to see if there's a tidy way of specifying the puzzle input. For example Day 2's input looks like;

1x2x3
1x3x6
...
...

So I'm thinking we almost want a function like;

(parse-input "day02.input" "<int>x<int>x<int>")

;; -> ((1 2 3) (1 3 6) ... ...)

Usually I'd either split or use regex for input, but it seems like what I'd like is to also be able to specify the basic type. Puzzle 8's example;

London to Dublin = 464
London to Belfast = 518
Dublin to Belfast = 141

Would be;

(parse-input "day08.input" "<string> to <string> = <int>")

;; -> (("London" "Dublin" 464) ...)

Or even better!

(parse-input "day08.input" "<string:from> to <string:to> = <int:distance>")
;; -->
({:from "London" :to "Dublin" :distance 464} ...)

I'd be interested if you know of anything like this feature.

End

I'll carry on with some more problems. I don't think I'll be entering any leaderboards soon ... unless there are some for slowest?