From d76ac78c7f044b2e39849eaed2db5fa67390875b Mon Sep 17 00:00:00 2001
From: Xavier Morel <morelx42@gmail.com>
Date: Wed, 5 Dec 2018 13:25:52 +0100
Subject: [PATCH] Adding day 4

---
 day4/part1.scala | 64 ++++++++++++++++++++++++++++++++++++++++++++++++
 day4/part2.scala | 56 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 120 insertions(+)
 create mode 100644 day4/part1.scala
 create mode 100644 day4/part2.scala

diff --git a/day4/part1.scala b/day4/part1.scala
new file mode 100644
index 0000000..fd2928c
--- /dev/null
+++ b/day4/part1.scala
@@ -0,0 +1,64 @@
+import scala.io.StdIn.readLine
+import java.time.{LocalDate, LocalTime}
+import java.time.format.DateTimeFormatter
+
+val fmt: DateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd kk:mm")
+
+case class Entry(shiftDate: LocalDate, time: LocalTime, id: Option[Int], sleep: Option[Boolean])
+
+def parseEntry(input: String): Entry = {
+  "\\[([^\\]]+)\\] ([^ ]+) ([^ ]+)".r.findFirstMatchIn(input).map {
+    m => 
+      val ts = fmt.parse(m.group(1))
+      val time = LocalTime.from(ts)
+      val shiftDate = time match {
+        case t if t.getHour == 23 => LocalDate.from(ts).plusDays(1L)
+        case _ => LocalDate.from(ts)
+      }
+
+      m.group(2) match {
+      case "Guard" => Entry(shiftDate, time, Some(m.group(3).drop(1).toInt), None)
+      case "falls" => Entry(shiftDate, time, None, Some(true))
+      case "wakes" => Entry(shiftDate, time, None, Some(false))
+    }
+  }.get
+}
+
+case class Sleep(id: Int, begin: LocalTime, end: LocalTime)
+
+def buildSleeps(input: List[Entry]): List[Sleep] = {
+  val guardNb = input.filter(_.id.nonEmpty).map(_.id.get).head
+  val sleepCycles = input.filter(e => e.sleep.nonEmpty).map(e => e.time -> e.sleep.get).sortBy(_._1.toSecondOfDay)
+  
+  (sleepCycles.filter(_._2).map(_._1) zip sleepCycles.filterNot(_._2).map(_._1))
+    .map(s => Sleep(guardNb, s._1, s._2))
+}
+
+val entries = Iterator
+  .continually(readLine)
+  .takeWhile(_ != null)
+  .map(parseEntry)
+  .toList
+
+val sleeps = entries.groupBy(_.shiftDate)
+  .flatMap { case (k, v) => buildSleeps(v) }
+
+val sleepers = sleeps
+  .groupBy(_.id).toList
+  .sortBy { case (k, v) => v.map(s => s.end.toSecondOfDay - s.begin.toSecondOfDay).sum }
+  .reverse
+
+val guardId = sleepers.head._1
+
+println(s"Guard ID: $guardId")
+
+val mostAsleepMinute = sleepers.head._2
+  .flatMap(s => s.begin.getMinute.to(s.end.getMinute - 1))
+  .groupBy(identity)
+  .mapValues(_.size)
+  .maxBy(_._2)
+  ._1
+
+println(s"Most asleep minute: $mostAsleepMinute")
+
+println(s"Result: ${guardId * mostAsleepMinute}")
diff --git a/day4/part2.scala b/day4/part2.scala
new file mode 100644
index 0000000..06d8d02
--- /dev/null
+++ b/day4/part2.scala
@@ -0,0 +1,56 @@
+import scala.io.StdIn.readLine
+import java.time.{LocalDate, LocalTime}
+import java.time.format.DateTimeFormatter
+
+val fmt: DateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd kk:mm")
+
+case class Entry(shiftDate: LocalDate, time: LocalTime, id: Option[Int], sleep: Option[Boolean])
+
+def parseEntry(input: String): Entry = {
+  "\\[([^\\]]+)\\] ([^ ]+) ([^ ]+)".r.findFirstMatchIn(input).map {
+    m => 
+      val ts = fmt.parse(m.group(1))
+      val time = LocalTime.from(ts)
+      val shiftDate = time match {
+        case t if t.getHour == 23 => LocalDate.from(ts).plusDays(1L)
+        case _ => LocalDate.from(ts)
+      }
+
+      m.group(2) match {
+      case "Guard" => Entry(shiftDate, time, Some(m.group(3).drop(1).toInt), None)
+      case "falls" => Entry(shiftDate, time, None, Some(true))
+      case "wakes" => Entry(shiftDate, time, None, Some(false))
+    }
+  }.get
+}
+
+case class Sleep(id: Int, begin: LocalTime, end: LocalTime)
+
+def buildSleeps(input: List[Entry]): List[Sleep] = {
+  val guardNb = input.filter(_.id.nonEmpty).map(_.id.get).head
+  val sleepCycles = input.filter(e => e.sleep.nonEmpty).map(e => e.time -> e.sleep.get).sortBy(_._1.toSecondOfDay)
+  
+  (sleepCycles.filter(_._2).map(_._1) zip sleepCycles.filterNot(_._2).map(_._1))
+    .map(s => Sleep(guardNb, s._1, s._2))
+}
+
+val entries = Iterator
+  .continually(readLine)
+  .takeWhile(_ != null)
+  .map(parseEntry)
+  .toList
+
+val sleeps = entries.groupBy(_.shiftDate)
+  .flatMap { case (k, v) => buildSleeps(v) }
+
+val res = sleeps
+  .flatMap ( s => s.begin.getMinute.to(s.end.getMinute - 1).map(m => m -> s.id))
+  .groupBy(identity)
+  .mapValues(_.size)
+  .toList
+  .sortBy(_._2)
+  .last
+
+println(s"Guard ${res._1._1} slept during minute ${res._1._2}, ${res._2} times.")
+
+println(s"Result: ${res._1._1 * res._1._2}")