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# Advent of Code 2025
Run with Python. Input is read from the file given as argument, or
from standard input if no argument is provided.
Example
`python 01/a.py 01/input.txt`
## Personal times
```
Day -Part 1- -Part 2-
4 00:25:36 00:27:49
3 00:05:02 00:16:09
2 00:10:36 00:11:55
1 00:06:20 00:50:41
```
## Daily comments (spoilers!)
### Day 1: Secret Entrance
Part 1 was easy. Well, I misread the statement and got it wrong twice,
but that's on me.
Then I kept getting part 2 wrong, and I have no idea what I was doing wrong.
Sure, at first I made some mistakes related to landing on zero at the
end of a movement. But for at least 6-7 times I found a mistake, fixed,
my code would solve the example case correctly but my answer on the real
input was wrong. At some point I started rewriting the code in alternative
ways hoping to get a different answer, and one of those versions worked.
Still no idea why.
So in the end it took me more than 40 minutes to solve part 2. Great start!
### Day 1: Secret Entrance
I misread the statement for part 1 and I accidentally solved part 2 first.
I re-read the problem description, fixed my code, submitted it, and then
I just had to press `Ctrl+Z` (actually `u` on vi...) enough times to solve
part 2.
### Day 3: Lobby
My solution for part 1 is ad-hoc and not very good. I should have thought
about it a bit longer, the general solution isn't much harder to find.
For part 2 I used recursion with memorization (using Python's
`functools.cache`), which is fast enough. But later Chiara pointed
out to me that actually the solution is quite trivially greedy; I
implemented the greedy version in `b-alt.py`.
### Day 4: Printing Department
The first "map" problem of the year! This one was easy, but I
made a lot of mistakes in part 1. I decided to use the trick that
[Jared](https://guissmo.com) suggested a couple of years ago: extend the
map by 1 cell in all directions so you don't have to deal with indices
out of bounds.
For part 2 I decided to quickly code the dumb "repeat part 1 until no
rolls are removed" strategy and it worked.
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