Day 19 - Linen Layout
Megathread guidelines
- Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
- You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL
FAQ
- What is this?: Here is a post with a large amount of details: https://programming.dev/post/6637268
- Where do I participate?: https://adventofcode.com/
- Is there a leaderboard for the community?: We have a programming.dev leaderboard with the info on how to join in this post: https://programming.dev/post/6631465
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3 points
*
Dart
Thanks to this useful post for reminding me that dynamic programming exists (and for linking to a source to help me remember how it works as it always makes my head spin :-) I guessed that part 2 would require counting solutions, so that helped too.
Solves live data in about 40ms.
import 'package:collection/collection.dart';
import 'package:more/more.dart';
int countTarget(String target, Set<String> towels) {
int n = target.length;
List<int> ret = List.filled(n + 1, 0)..[0] = 1;
for (int e in 1.to(n + 1)) {
for (int s in 0.to(e)) {
if (towels.contains(target.substring(s, e))) ret[e] += ret[s];
}
}
return ret[n];
}
List<int> allCounts(List<String> lines) {
var towels = lines.first.split(', ').toSet();
return lines.skip(2).map((p) => countTarget(p, towels)).toList();
}
part1(List<String> lines) => allCounts(lines).where((e) => e > 0).length;
part2(List<String> lines) => allCounts(lines).sum;
3 points
