Advent Of Code

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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

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💂 - 2024 DAY 6 SOLUTIONS - 💂 (programming.dev)

submitted 3 weeks ago by [email protected] to c/[email protected]

41 comments fedilink hide all child comments

Day 6: Guard Gallivant

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[–] [email protected] 2 points 3 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 3 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.

[–] [email protected] 1 points 3 weeks ago

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

[–] [email protected] 2 points 3 weeks ago* (last edited 3 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.