2022 Day 4 Scala

2022/day4.scala

@@ -0,0 +1,17 @@
+import scala.io.Source
+
+val numberPattern = raw"((?:(?<!\d)-)?\d+)".r
+
+extension (s: String) def splitHalf: (String, String) = (s.substring(0, s.length()/2), s.substring(s.length()/2))
+
+@main def main() =
+	val rangePairs: Array[(Range, Range)] = Source.fromFile("input/4").getLines
+		.map(line => numberPattern.findAllIn(line).map(_.toInt).toArray)
+		.map(n => ((n(0) to n(1)), (n(2) to n(3))))
+		.toArray  // Can't leave it lazy as Part 1 will consume it
+
+	val subsets = rangePairs.map((a,b) => if (a.containsSlice(b) | b.containsSlice(a)) 1 else 0).sum
+	println(s"Part 1: $subsets elves have no unique work in their pairing")
+
+	val overlaps = rangePairs.map((a,b) => if (a.intersect(b).isEmpty) 0 else 1).sum
+	println(s"Part 2: $overlaps elf pairs have overlapping work in their pairing")