Advent Of Code

979 readers

19 users here now

An unofficial home for the advent of code community on programming.dev!

Advent of Code is an annual Advent calendar of small programming puzzles for a variety of skill sets and skill levels that can be solved in any programming language you like.

AoC 2024

Solution Threads

M	T	W	T	F	S	S
						1
2	3	4	5	6	7	8
9	10	11	12	13	14	15
16	17	18	19	20	21	22
23	24	25

Rules/Guidelines

Follow the programming.dev instance rules
Keep all content related to advent of code in some way
If what youre posting relates to a day, put in brackets the year and then day number in front of the post title (e.g. [2024 Day 10])
When an event is running, keep solutions in the solution megathread to avoid the community getting spammed with posts

Relevant Communities

Relevant Links

Advent of Code Homepage

Credits

Icon base by Lorc under CC BY 3.0 with modifications to add a gradient

console.log('Hello World')

founded 1 year ago

MODERATORS

Ategon

[email protected]

CameronDev

💂 - 2024 DAY 6 SOLUTIONS - 💂 (self.advent_of_code)

submitted 2 weeks ago by CameronDev to c/advent_of_code

41 comments fedilink hide all child comments

Day 6: Guard Gallivant

Megathread guidelines

Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
Where do I participate?: https://adventofcode.com/
Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465

you are viewing a single comment's thread
view the rest of the comments

[–] CameronDev 3 points 2 weeks ago (4 children)

How long did brute force take? Mine was 9s on an m1 with rust.

[–] Deebster 3 points 2 weeks ago* (last edited 2 weeks ago)

My rust code ran in 6s on my phone (Samsung A35 running under Termux). When I'm back at a computer it'd be interesting to compare times properly.

[–] Pyro 2 points 2 weeks ago* (last edited 2 weeks ago) (1 children)

About 15-20 seconds, not too bad.

[–] CameronDev 1 points 2 weeks ago* (last edited 2 weeks ago)

I got mine down to 3s, but it wasn't a very smart loop detection. All I did was count steps and stop after 10000. The 9 second run was 100000 steps, which is obviously a bit excessive.

Does save iterating over the list of past visits, so probably a good shortcut.

[–] [email protected] 1 points 2 weeks ago* (last edited 2 weeks ago)

I did a similar approach (place obstacles on guards path). Takes about ~~80s~~ 10-15s in 11th Gen Intel(R) Core(TM) i7-11800H. Motivated by the code above, I also restricted the search to start right before the obstacle rather than the whole path which took it down from 80s to 10-15s

[–] [email protected] 1 points 2 weeks ago (1 children)

Mine was 9s

That's about how long it takes for my python solution to complete.

[–] CameronDev 2 points 2 weeks ago (2 children)

How did you detect loops? I just ran for 100000 steps to see if I escaped, got my time down to 3s by doing only 10000 steps.

[–] [email protected] 2 points 2 weeks ago* (last edited 2 weeks ago)

I added each visited position/direction to a set, and when a 'state' is reached again you have entered a loop:

v = set()
while t[g.r][g.c] != 'X':
    state = (g.r, g.c, g.d)
    if state in v:
        acc += 1
        break
    v.add(state)
    g.move(t)

You can view my full solution here.

[–] [email protected] 2 points 2 weeks ago (1 children)

Not who you asked but: I save coordinates and direction into a vector each time the guard faces a #. Also every time the guard faces a #, I check if the position exists in the vector, if true, it’s an infinite loop. 78ms rust aolution.

[–] CameronDev 1 points 2 weeks ago

That's probably quite optimal, compared with checking every state in the path, or running off a fixed number of steps