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Clean up 2024 day 14
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@sim642
sim642 committed Dec 14, 2024
1 parent fcb53f4 commit 9b2acce
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Showing 2 changed files with 145 additions and 14 deletions.
45 changes: 32 additions & 13 deletions src/main/scala/eu/sim642/adventofcode2024/Day14.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -9,28 +9,44 @@ object Day14 {
// copied from 2021 day 25
extension (pos: Pos) {
def %+(other: Pos): Pos = Pos(pos.x %+ other.x, pos.y %+ other.y)
infix def compareTo(other: Pos): Pos = Pos(pos.x `compareTo` other.x, pos.y `compareTo` other.y)
def sign: Pos = Pos(pos.x.sign, pos.y.sign)
}

case class Robot(pos: Pos, velocity: Pos) {
def step(roomSize: Pos): Robot = Robot((pos + velocity) %+ roomSize, velocity)
def step(t: Int, roomSize: Pos): Robot = Robot((pos + t *: velocity) %+ roomSize, velocity)
}

def safetyFactor(robots: Seq[Robot], roomSize: Pos = Pos(101, 103)): Int = {
val inputRoomSize: Pos = Pos(101, 103)

def safetyFactor(robots: Seq[Robot], roomSize: Pos = inputRoomSize): Int = {
val newRobots = robots.map(_.step(100, roomSize))
//newRobots.foreach(println)
val roomMiddle = Pos(roomSize.x / 2, roomSize.y / 2)
//println(roomMiddle)
//val quadrants0 = newRobots.groupBy(robot => (robot.pos.x.compare(roomMiddle.x), robot.pos.y.compare(roomMiddle.y))).withDefaultValue(0)
//quadrants0.foreach(println)
val quadrants = newRobots.groupCount(robot => (robot.pos.x.compare(roomMiddle.x), robot.pos.y.compare(roomMiddle.y))).withDefaultValue(0)
quadrants((1, 1)) * quadrants((-1, 1)) * quadrants((1, -1)) * quadrants((-1, -1))
val quadrants = newRobots.groupCount(robot =>
(robot.pos `compareTo` roomMiddle).sign // use .sign to clamp to -1, 0, 1
).withDefaultValue(0)
Pos.diagonalOffsets.map(quadrants).product
}

def findEasterEgg(robots: Seq[Robot], roomSize: Pos = Pos(101, 103)): Int = {
Iterator.from(0)
.map(t => robots.map(_.step(t, roomSize))) // TODO: optimize
.map(newRobots => newRobots.groupCount(_.pos))
.indexWhere(_.values.forall(_ <= 1)) // look for arrangement with unique positions
def findEasterEgg(robots: Seq[Robot], roomSize: Pos = inputRoomSize): (Seq[Robot], Int) = {
Iterator.iterate(robots)(_.map(_.step(roomSize)))
.zipWithIndex
.find(_._1.groupCount(_.pos).values.forall(_ <= 1)) // look for arrangement with unique positions
// TODO: optimize by stopping groupCount when some goes over 1
.get
}

def printRobots(robots: Seq[Robot], roomSize: Pos = inputRoomSize): Unit = {
val posRobots = robots.groupCount(_.pos)

for (y <- 0 until roomSize.y) {
for (x <- 0 until roomSize.x) {
val pos = Pos(x, y)
print(posRobots.get(pos).map(count => ('0' + count).toChar).getOrElse('.')) // TODO: toDigit?
}
println()
}
}

def parseRobot(s: String): Robot = s match {
Expand All @@ -44,6 +60,9 @@ object Day14 {

def main(args: Array[String]): Unit = {
println(safetyFactor(parseRobots(input)))
println(findEasterEgg(parseRobots(input)))

val (easterEggRobots, easterEggTime) = findEasterEgg(parseRobots(input))
printRobots(easterEggRobots)
println(easterEggTime)
}
}
114 changes: 113 additions & 1 deletion src/test/scala/eu/sim642/adventofcode2024/Day14Test.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,8 @@ import Day14.*
import eu.sim642.adventofcodelib.pos.Pos
import org.scalatest.funsuite.AnyFunSuite

import java.io.ByteArrayOutputStream

class Day14Test extends AnyFunSuite {

val exampleInput =
Expand All @@ -29,6 +31,116 @@ class Day14Test extends AnyFunSuite {
}

test("Part 2 input answer") {
assert(findEasterEgg(parseRobots(input)) == 7093)
val (easterEggRobots, easterEggTime) = findEasterEgg(parseRobots(input))
assert(easterEggTime == 7093)

val out = new ByteArrayOutputStream()
Console.withOut(out) {
printRobots(easterEggRobots)
}
assert(out.toString.trim ==
""".........................1...........................................................................
|..............................1......................................................................
|.....................................................................................1.........1.....
|..............................................1.........................................1............
|.....................................................................................................
|.1.............1.....................................................................................
|.....................................................................................................
|......1.....1.......................................................1...................1............
|1.........................................................................1..........................
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|.....................................................................................................
|..............................................................................1................1.....
|................................1...1...............1..............................1.................
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|..................1...........1...................................................................1..
|.....................................................................................................
|.................1...........................1.......................................................
|................1..1................................1................................................
|.....................................................................................................
|.....................................................................................................
|............................1.1.....1111111111111111111111111111111..................................
|.1..................................1.............................1..................................
|....................................1.............................1..................................
|...1................................1.............................1..........................1.......
|..........................1.........1.............................1...................1..............
|....................................1..............1..............1..................................
|...............................1....1.............111.............1..................................
|....................................1............11111............1..................................
|....................................1...........1111111...........1......................1........1..
|....................................1..........111111111..........1............1................1....
|....................................1............11111............1........1.........................
|....................................1...........1111111...........1..................................
|.....................1............1.1..........111111111..........1.1............................1...
|....................................1.........11111111111.........1..................................
|....................................1........1111111111111........1..................................
|....................................1..........111111111..........1.1..................11............
|....................................1.........11111111111.........1..................................
|....................................1........1111111111111........1..................................
|......................1.............1.......111111111111111.......1..................................
|.......1............................1......11111111111111111......1..................................
|...........1..1.....................1........1111111111111........1................1.................
|....................................1.......111111111111111.......1...........................1......
|....................................1......11111111111111111......1.....1.................1..........
|......1.............................1.....1111111111111111111.....1..........1.......................
|................1...................1....111111111111111111111....1...................1..............
|..................................1.1.............111.............1..................................
|....................................1.............111.............1......1...........................
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|...............1....................1.............................1..............1...................
|..............1.........1...........1111111111111111111111111111111.....................1............
|...........................1........................................1................................
|....................1.....1................1..........................1..............................
|............................1........................................................................
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|.........................1......................................1....................................
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|.....................................................................................................
|.....................................................................................................
|...1............................................1..............1.....................................
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|....................................1.......1............1.......1.........................1.........
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|.....................................................................1.........1.................1...
|........................................1...........1...................1............................
|.................................................................1....1..............................
|...........................................1.........................................................
|.....................................................................................................
|.1....1............................................................................1.................
|.........................................................1...........................................
|..........................................................................................1..........
|...................................1........................................................1........
|........................1......................................1..........................1.1........
|.......1..................................................................1.........................1
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|.....................................................................................................
|..................................................................1................................1.
|.........................................................................1...........................
|..........................1..........................................................................
|.................................................................1...................................
|...........1.........................................................................................""".stripMargin)
}
}

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