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Advent of Code 2024 - Historian goes looking for history in all the wrong places (adventofcode.com)

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

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copy pasting the rules from last year's thread:

Rules: no spoilers.

The other rules are made up aswe go along.

Share code by link to a forge, home page, pastebin (Eric Wastl has one here) or code section in a comment.

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

For 3: I made dart one-liners for both. Pasting the juicy parts.

3:1

RegExp(r"mul\((\d*),(\d*)\)").allMatches(input).fold<int>( 0, (p, e) => p + e.groups([1, 2]).fold(1, (p, f) => p * int.parse(f!))));

3:2

My original solution found do, don't and mul entries, then stepped through them to get the solve. I decided to try regex my way through it. What I realised was that you want to ignore strings starting with don't() and ending at the first do(). Some amount of trial and error later, I figured out the (ecma*) regex to do it, which I am proud of:

RegExp(r"(?:don\'t\(\)(?:.(?<!do\(\)))*do\(\))|(?:mul\((\d*),(\d*)\))") .allMatches(input) .fold<int>( 0, (p, e) => p + (e.group(0)![0] != 'd' ? e.groups([1, 2]).fold<int>(1, (p, f) => p * int.parse(f!)) : 0))

*ecma balls