simplified 2015 day 05 (#18)

Author: nmcb

2015/src/main/scala/Day05.scala

@@ -2,55 +2,26 @@ import scala.io.*
 
 object Day05 extends App:
 
-  val day: String =
-    this.getClass.getName.drop(3).init
-
-  val start1: Long =
-    System.currentTimeMillis
+  val day: String  = getClass.getName.filter(_.isDigit).mkString
 
   val strings: List[String] =
     Source
       .fromResource(s"input$day.txt")
       .getLines
       .toList
 
-  val answer1: Int =
-    val valid = for {
-      str <- strings
-      if str.count("aeiou".toList.contains) >= 3
-      if str.sliding(2).map(_.toArray).count(cs => cs(0) == cs(1)) >= 1
-      if str.sliding(2).count(cs => cs == "ab" || cs == "cd" || cs == "pq" || cs == "xy") == 0
-    } yield str
-    valid.size
+  val vowels  = "[aeiou].*[aeiou].*[aeiou]".r.unanchored
+  val pair    = "(.)\\1".r.unanchored
+  val naughty = "ab|cd|pq|xy".r.unanchored
 
+  val start1: Long = System.currentTimeMillis
+  val answer1: Int = strings.count(line => vowels.matches(line) && pair.matches(line) && !naughty.matches(line))
   println(s"Answer AOC 2015 day $day part 1: ${answer1} [${System.currentTimeMillis - start1}ms]")
 
-  val start2: Long =
-    System.currentTimeMillis
-
-  val answer2: Int =
-    def containsTwoOrMoreNonOverlappingPair(str: String): Boolean =
-      def hasNonOverlappingPair(pair: String, todo: String, foundFirst: Boolean = false): Boolean =
-        val index = todo.indexOf(pair)
-        if      (index != -1 && !foundFirst) hasNonOverlappingPair(pair, todo.drop(index + 2), true)
-        else if (index != -1 &&  foundFirst) true
-        else                                 false
-
-      (str.sliding(2).distinct).exists(pair => hasNonOverlappingPair(pair, str)) 
-
-    def containsTwoSameCharsOneCharApart(str: String): Boolean =
-      def hasTwoSameCharsOneCharApart(todo: List[Char]): Boolean =
-        todo match
-          case c0 ::  _ :: c2 :: tail if c0 == c2 => true
-          case c0 :: c1 :: c2 :: tail             => hasTwoSameCharsOneCharApart(c1 :: c2 :: tail)
-          case _                                  => false
-      hasTwoSameCharsOneCharApart(str.toList)
-
-    val filter = for {
-      str <- strings
-      if containsTwoOrMoreNonOverlappingPair(str)
-      if containsTwoSameCharsOneCharApart(str)
-    } yield str
-    filter.size
-  
+
+  val twoPair = "(..).*\\1".r.unanchored
+  val triple  = "(.).\\1".r.unanchored
+
+  val start2: Long = System.currentTimeMillis
+  val answer2: Int = strings.count(line => twoPair.matches(line) && triple.matches(line))
   println(s"Answer AOC 2015 day $day part 2: ${answer2} [${System.currentTimeMillis - start2}ms]")