Advent Of Code

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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 2 SOLUTIONS -🦌 (programming.dev)

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

57 comments fedilink hide all child comments

Day 2: Red-Nosed Reports

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[–] [email protected] 3 points 3 weeks ago (1 children)

I don't think your solution is O(N^3). Can you explain your reasoning?

[–] [email protected] 1 points 3 weeks ago (1 children)

3 nested for loops

[–] [email protected] 2 points 3 weeks ago (1 children)

It's not as simple as that. You can have 20 nested for loops with complexity of O(1) if all of them only ever finish one iteration.

Or you can have one for loop that iterates 2^N times.

[–] [email protected] 1 points 3 weeks ago (2 children)

What do you think my complexity is?

I think it could be maybe O(n^2) because the other for loop which tries elements around the first error will only execute a constant of 5 times in the worst case? I'm unsure.

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

It's O(n).

If you look at each of the levels of all reports, you will access it a constant number of times: at most twice in each call to EvaluateLineSafe, and you will call EvaluateLineSafe at most six times for each report.

[–] [email protected] 2 points 3 weeks ago

It really depends on what your parameter n is. If the only relevant size is the number of records (let's say that is n), then this solution takes time in O(n), because it loops over records only once at a time. This ignores the length of records by considering it constant.

If we also consider the maximum length of records (let's call it m), then your solution, and most others I've seen in this thread, has a time complexity in O(n * m^2) for part 2.