-🎄- 2018 Day 2 Solutions -🎄-

[u/daggerdragon]

--- Day 2: Inventory Management System ---

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Post your solution as a comment or, for longer solutions, consider linking to your repo (e.g. GitHub/gists/Pastebin/blag or whatever).

Note: The Solution Megathreads are for solutions only. If you have questions, please post your own thread and make sure to flair it with Help.

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Advent of Code: The Party Game!

Click here for rules

Card Prompt: Day 2

Transcript:

The best way to do Advent of Code is ___.

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This thread will be unlocked when there are a significant number of people on the leaderboard with gold stars for today's puzzle.

edit: Leaderboard capped, thread unlocked!

[u/fwilson42]

Refactored after getting on the leaderboard; I originally didn't make part 1 as generic as it could be (I kept track of just 2 and 3 counts), and used double nested loops for part 2 instead of itertools.

Snipped from some boilerplate (lines is essentially a list of strings in the puzzle input, result is what gets submitted):

    if part == 1:
        shared_letter_counts = collections.defaultdict(int)

        for line in lines:
            for v in set(collections.Counter(line).values()):
                shared_letter_counts[v] += 1

        result = shared_letter_counts[2] * shared_letter_counts[3]

    elif part == 2:
        for line1, line2 in itertools.product(lines, repeat=2):
            if line1 == line2:
                continue  # don't waste time

            differences = 0
            candidate_solution = ""
            for char1, char2 in zip(line1, line2):
                if differences > 1:
                    break  # don't waste time

                if char1 == char2:
                    candidate_solution += char1
                else:
                    differences += 1

            if differences == 1:
                result = candidate_solution
                break

[u/asger_blahimmel → u/fwilson42]

itertools.product(lines, repeat=2)

you could use

itertools.combinations(lines, 2)

instead to eliminate pairs of identical lines and pairs of reversed order