Adding day 12

2026-01-14 13:59:51 +01:00 · 2018-12-12 11:05:26 +01:00
parent 2eefb86570
commit b93c69bf0b
2 changed files with 149 additions and 0 deletions
--- a/day12/part1.scala
+++ b/day12/part1.scala
@@ -0,0 +1,61 @@
+import scala.io.StdIn.readLine
+
+val LAST_GEN = 130
+
+case class Rule(m2: Boolean, m1: Boolean, o: Boolean, p1: Boolean, p2: Boolean, r: Boolean) {
+  def computePot(n: Int, input: Set[Int]): Option[Int] =
+      if (input.contains(n - 2) == m2 &&
+          input.contains(n - 1) == m1 &&
+          input.contains(n) == o &&
+          input.contains(n + 1) == p1 &&
+          input.contains(n + 2) == p2 &&
+          r) {
+            Some(n)
+          } else {
+            None
+          }
+}
+
+def parseRule(in: String): Option[Rule] =
+  (("(#|\\.)" * 5) + " => (#|\\.)").r.findFirstMatchIn(in).map(
+    m => Rule(m.group(1) == "#", m.group(2) == "#", m.group(3) == "#", m.group(4) == "#", m.group(5) == "#", m.group(6) == "#")
+  )
+
+def computeGeneration(current: Set[Int], rules: List[Rule]): Set[Int] =
+  ((current.min - 2).to(current.max + 2))
+    .flatMap(k => rules.flatMap(_.computePot(k, current)).headOption)
+    .toSet
+
+def printGeneration(min: Int, max: Int)(gen: (Int, Set[Int])): Unit = gen match {
+  case (id, pots) =>
+    val chars = pots.map(k => k -> '#').toMap.withDefaultValue('.')
+    val str = List.range(min, max, 1).map(chars).mkString("")
+    val sum = pots.sum
+    println(s"$id: $str $sum")
+}
+
+val initialStateReg = "^initial state: ((?:#|\\.)+)$".r
+
+val origInit = readLine
+
+val init = initialStateReg.findFirstMatchIn(origInit)
+  .map(m => m.group(1)).get
+  .zipWithIndex.flatMap {
+    case ('.', i) => None
+    case ('#', i) => Some(i)
+  }
+.toSet
+
+val rules = Iterator
+  .continually(readLine)
+  .takeWhile(_ != null)
+  .flatMap(parseRule)
+  .toList
+
+val gens = List.range(1, LAST_GEN + 1, 1).scanLeft(0 -> init) {
+  case (gen, id) => id -> computeGeneration(gen._2, rules) }
+
+val min = gens.map(_._2.min).min - 2
+val max = gens.map(_._2.max).max + 2
+
+gens.foreach(printGeneration(min, max))
--- a/day12/part2.scala
+++ b/day12/part2.scala
@@ -0,0 +1,88 @@
+import scala.io.StdIn.readLine
+
+val LAST_GEN = 5000
+
+case class Rule(m2: Boolean, m1: Boolean, o: Boolean, p1: Boolean, p2: Boolean, r: Boolean) {
+  def computePot(n: Int, input: Set[Int]): Option[Int] =
+      if (input.contains(n - 2) == m2 &&
+          input.contains(n - 1) == m1 &&
+          input.contains(n) == o &&
+          input.contains(n + 1) == p1 &&
+          input.contains(n + 2) == p2 &&
+          r) {
+            Some(n)
+          } else {
+            None
+          }
+}
+
+def parseRule(in: String): Option[Rule] =
+  (("(#|\\.)" * 5) + " => (#|\\.)").r.findFirstMatchIn(in).map(
+    m => Rule(m.group(1) == "#", m.group(2) == "#", m.group(3) == "#", m.group(4) == "#", m.group(5) == "#", m.group(6) == "#")
+  )
+
+def computeGeneration(current: Set[Int], rules: List[Rule]): Set[Int] =
+  ((current.min - 2).to(current.max + 2))
+    .flatMap(k => rules.flatMap(_.computePot(k, current)).headOption)
+    .toSet
+
+def printGeneration(min: Int, max: Int)(gen: (Int, Set[Int])): Unit = gen match {
+  case (id, pots) =>
+    val chars = pots.map(k => k -> '#').toMap.withDefaultValue('.')
+    val str = List.range(min, max, 1).map(chars).mkString("")
+    val sum = pots.sum
+    println(s"$id: $str $sum")
+}
+
+val initialStateReg = "^initial state: ((?:#|\\.)+)$".r
+
+val origInit = readLine
+
+val init = initialStateReg.findFirstMatchIn(origInit)
+  .map(m => m.group(1)).get
+  .zipWithIndex.flatMap {
+    case ('.', i) => None
+    case ('#', i) => Some(i)
+  }
+.toSet
+
+val rules = Iterator
+  .continually(readLine)
+  .takeWhile(_ != null)
+  .flatMap(parseRule)
+  .toList
+
+val gens = List.range(1, LAST_GEN + 1, 1).scanLeft(0 -> init) {
+  case (gen, id) => id -> computeGeneration(gen._2, rules) }
+// val min = gens.map(_._2.min).min - 2
+// val max = gens.map(_._2.max).max + 2
+// gens.foreach(printGeneration(min, max))
+/**
+ * After ~100 generations, the same pattern simply moves
+ * 38 pots
+ * min pot = generation id - 80
+ * max pot = generation id + 98
+ #....#....#....#....#....#....#....#....#....#....#....#....#....#....#....#....#....#...#....#...#...#...#....#....#....#....#....#....#....#...#...#....#...#....#....#....#....#
+ *
+ * Observed that :
+ * GenerationId = (Sum - 4) / 38 - 10
+ * -> Sum = ((GenerationId + 10) * 38) + 4
+ */
+
+def printGenData(id: Int, gen: Set[Int]): Unit = {
+  val cnt = gen.size
+  val sum = gen.sum
+  val x = (sum - 4) / 38.0 - 10
+  val guess = ((id + 10) * 38) + 4
+
+  println(s"Generation $id")
+  println(s"CNT(p) = $cnt")
+  println(s"SUM(p) = $sum")
+  println(x)
+  println(s"Guess = $guess")
+  println("")
+}
+
+List(100, 101, 110, 120, 130, 140, 150, 200, 300, 500, 1000, 5000).foreach(g => printGenData(g, gens(g)._2))
+
+println((50000000000L + 10) * 38 + 4)