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)
Code block support is not fully rolled out yet but likely will be in the middle of the event. Try to share solutions as both code blocks and using something such as https://topaz.github.io/paste/ , pastebin, or github (code blocks to future proof it for when 0.19 comes out and since code blocks currently function in some apps and some instances as well if they are running a 0.19 beta)
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
š Thread is locked until there's at least 100 2 star entries on the global leaderboard
Terrible monkey-coding approach of banging strings together and counting the resulting shards. Just kept to a reasonable 300ms runtime by a bit of memoisation of results. I'm sure this can all be replaced by a single line of clever combinatorial wizardry.
var __countMatches = {};
int _countMatches(String pattern, List counts) =>
__countMatches.putIfAbsent(
pattern + counts.toString(), () => countMatches(pattern, counts));
int countMatches(String pattern, List counts) {
if (!pattern.contains('#') && counts.isEmpty) return 1;
if (pattern.startsWith('..')) return _countMatches(pattern.skip(1), counts);
if (pattern == '.' || counts.isEmpty) return 0;
var thisShape = counts.first;
var minSpaceForRest =
counts.length == 1 ? 0 : counts.skip(1).sum + counts.skip(1).length + 1;
var lastStart = pattern.length - minSpaceForRest - thisShape;
if (lastStart < 1) return 0;
var total = 0;
for (var start in 1.to(lastStart + 1)) {
// Skipped a required spring. Bad, and will be for all successors.
if (pattern.take(start).contains('#')) break;
// Includes a required separator. Also bad.
if (pattern.skip(start).take(thisShape).contains('.')) continue;
var rest = pattern.skip(start + thisShape);
if (rest.startsWith('#')) continue;
// force '.' or '?' to be '.' and count matches.
total += _countMatches('.${rest.skip(1)}', counts.skip(1).toList());
}
return total;
}
solve(List lines, {stretch = 1}) {
var ret = [];
for (var line in lines) {
var ps = line.split(' ');
var pattern = List.filled(stretch, ps.first).join('?');
var counts = List.filled(stretch, ps.last)
.join(',')
.split(',')
.map(int.parse)
.toList();
ret.add(countMatches('.$pattern.', counts)); // top and tail.
}
return ret.sum;
}
part1(List lines) => solve(lines);
part2(List lines) => solve(lines, stretch: 5);