feat: day 8

2015/Day8.scala

@@ -0,0 +1,31 @@
+package day8
+
+import scala.io.Source.fromFile
+import scala.util.chaining.*
+
+extension (s: String)
+  def memoryLen = decode(s.toList).size - 2
+  def encodedLen = encode(s.toList).size + 2
+
+def decode(sx: List[Char]): List[Char] = sx match
+  case '\\' :: '\\' :: xs          => '\\' +: decode(xs)
+  case '\\' :: '"' :: xs           => '"' +: decode(xs)
+  case '\\' :: 'x' :: _ :: _ :: xs => 'x' +: decode(xs)
+  case x :: xs                     => x +: decode(xs)
+  case Nil                         => Nil
+
+def encode(sx: List[Char]): List[Char] = sx match
+  case '\\' :: xs => '\\' +: '\\' +: encode(xs)
+  case '"' :: xs  => '\\' +: '"' +: encode(xs)
+  case x :: xs    => x +: encode(xs)
+  case Nil        => Nil
+
+def part1(s: String) = s.size - s.memoryLen
+def part2(s: String) = s.encodedLen - s.size
+
+@main def main() =
+  val input =
+    fromFile(".cache/08.txt").getLines.toVector.map(_.trim)
+
+  input.map(part1).sum.pipe(println)
+  input.map(part2).sum.pipe(println)

2015/Day8.test.scala

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+import munit.FunSuite
+import day8.*
+
+class Day8Tests extends FunSuite:
+  val xs = Seq(
+    """""""" -> (2, 0),
+    """"abc"""" -> (5, 3),
+    """"aaa\"aaa"""" -> (10, 7),
+    """"\x27"""" -> (6, 1),
+  )
+
+  xs.foreach { (x, rest) =>
+    val (literalLen, memoryLen) = rest
+    test(s"part1 [$x]"):
+      assertEquals(x.size, literalLen)
+      assertEquals(x.memoryLen, memoryLen)
+      assertEquals(part1(x), literalLen - memoryLen)
+  }
+
+  test("part1"):
+    assertEquals(xs.map(_._1).map(part1).sum, 12)
+
+  val ys = Seq(
+    """""""" -> (2, 6),
+    """"abc"""" -> (5, 9),
+    """"aaa\"aaa"""" -> (10, 16),
+    """"\x27"""" -> (6, 11),
+  )
+
+  ys.foreach { (y, rest) =>
+    val (literalLen, encodedLen) = rest
+    assertEquals(y.size, literalLen)
+    assertEquals(y.encodedLen, encodedLen)
+    assertEquals(part2(y), encodedLen - literalLen)
+  }
+
+  test("part2"):
+    assertEquals(ys.map(_._1).map(part2).sum, 19)