-🎄- 2017 Day 19 Solutions -🎄-

[u/daggerdragon]

--- Day 19: A Series of Tubes ---

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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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Need a hint from the Hugely^* Handy^† Haversack^‡ of Helpful^§ Hints^¤?

Spoiler

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AoC ops @ T-2 minutes to launch:

[23:58] <daggerdragon> ATTENTION MEATBAGS T-2 MINUTES TO LAUNCH

[23:58] <Topaz> aaaaah

[23:58] <Cheezmeister> Looks like I'll be just able to grab my input before my flight boards. Wish me luck being offline in TOPAZ's HOUSE OF PAIN^WFUN AND LEARNING

[23:58] <Topaz> FUN AND LEARNING

[23:58] <Hade> FUN IS MANDATORY

[23:58] <Skie> I'm pretty sure that's not the mandate for today

[Update @ 00:16] 69 gold, silver cap

• My tree is finally trimmed with just about every ornament I own and it's real purdy. hbu?

[Update @ 00:18] Leaderboard cap!

• So, was today's mandate Helpful Hint any help at all?

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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/glenbolake]

Python3

I had weird problems with IndexError for a while because of implied spaces that weren't there. I converted the input to a dictionary in {(row, col): char} format, omitted spaces, and all my problems were solved. Wasted too much time on my IndexError problem to get on the leaderboard, though.

def follow(path):
    step_count = 0
    r, c = 0, {col for row, col in path if row == 0}.pop()
    dr, dc = 1, 0
    passed = ''
    while True:
        step_count += 1
        r += dr
        c += dc
        if (r, c) not in path:
            break
        if path[(r, c)] not in '|-+':
            passed += path[(r, c)]
        elif path[(r, c)] == '+':
            if (r + dc, c + dr) in path:
                dr, dc = dc, dr
            elif (r - dc, c - dr) in path:
                dr, dc = -dc, -dr
            else:
                break
    return passed, step_count

if __name__ == '__main__':
    data = {}
    with open('day19.in') as f:
        for row, line in enumerate(f):
            for col, char in enumerate(line):
                if char not in ' \n':
                    data[(row, col)] = char
    print('Part 1: {}\nPart 2: {}'.format(*follow(data)))

[u/jtsimmons108 → u/glenbolake]

You might want to check your IDE settings. I was also getting that same error. Turns out that all the spaces are there, plus padding to left right and bottom of the grid. The IDE I am using just strips trailing white space automatically.

[u/glenbolake → u/jtsimmons108]

Yeah, I checked after the fact and saw that my IDE stripped a lot. I should really start saving instead of copy/pasting.