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Day 11 (Make fast when hot)

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Christian
2024-12-15 12:31:08 +01:00
parent 10d9d3452f
commit 7bd424d1f9
1 changed files with 17 additions and 19 deletions
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36
aoc/src/dev/ctsk/aoc/days/Day11.scala
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@@ -11,28 +11,26 @@ object Day11 extends Solver(11):
val mod = Math.pow(10, numDigits / 2).toLong val mod = Math.pow(10, numDigits / 2).toLong
Some(n % mod, n / mod) Some(n % mod, n / mod)
private def count(initial: Seq[Long], depth: Int): Long = private val memo = MuMap.empty[(Long, Int), Long]
def step(stones: MuMap[Long, Long]): MuMap[Long, Long] = private def count(initial: Long, numBlinks: Int): Long =
val next = MuMap.empty[Long, Long].withDefaultValue(0L) def rec(stone: Long, blinks: Int): Long =
for ((stone, count) <- stones) { if blinks == 0 then return 1L
if stone == 0 then next(1) += count memo.getOrElseUpdate(
else (stone, blinks), {
halves(stone) match if stone == 0 then rec(1L, blinks - 1)
case Some((a, b)) => else
next(a) += count halves(stone) match
next(b) += count case Some(a, b) =>
case None => rec(a, blinks - 1) + rec(b, blinks - 1)
next(stone * 2024) += count case None => rec(stone * 2024, blinks - 1)
} }
next )
rec(initial, numBlinks)
val initMap = MuMap.from(initial.map((_, 1L)))
Seq.iterate(initMap, depth + 1)(step).last.values.sum
def run(input: os.ReadablePath): (Timings, Solution) = def run(input: os.ReadablePath): (Timings, Solution) =
val (pre_time, in) = timed { longs(os.read.lines(input).head) } val (pre_time, in) = timed { longs(os.read.lines(input).head) }
val (p1_time, p1_solution) = timed { count(in, 25) } val (p1_time, p1_solution) = timed { in.map(v => count(v, 25)).sum }
val (p2_time, p2_solution) = timed { count(in, 75) } val (p2_time, p2_solution) = timed { in.map(v => count(v, 75)).sum }
( (
Timings(pre_time, p1_time, p2_time), Timings(pre_time, p1_time, p2_time),