/Advent of Code 10.scala Secret
Created
February 12, 2021 11:39
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import java.io.FileInputStream | |
import scala.io.StdIn | |
@main def solve10() = | |
def solve1(numbers: Vector[Int]): Int = { | |
val jolts = 0 +: numbers.sorted :+ (numbers.max + 3) | |
val gabs = jolts.sliding(2).foldLeft(Map[Int, Int]()) { (acc, x) => | |
val gab = x(1) - x(0) | |
acc.updated(gab, acc.getOrElse(gab, 0) + 1) | |
} | |
gabs(1) * gabs(3) | |
} | |
def solve2(numbers: Vector[Int]): BigInt = { | |
val jolts = 0 +: numbers.sorted :+ (numbers.max + 3) | |
val numberOfWaysToArrange = jolts.indices.foldLeft(Array.fill(jolts.size)(BigInt(0))) { (acc, idx) => | |
if 0 == idx then | |
acc(idx) = 1 | |
else | |
(1 to 3).foreach(delta => | |
if 0 <= idx - delta && 3 >= jolts(idx) - jolts(idx - delta) then | |
acc(idx) += acc(idx - delta) | |
) | |
acc | |
} | |
numberOfWaysToArrange.last | |
} | |
val in = new FileInputStream("example10-1.in") | |
System.setIn(in) | |
val inputs = Iterator.continually(StdIn.readLine()).takeWhile(_ != null).toVector | |
val numbers = inputs.map { line => line.toInt } | |
val answer1 = solve1(numbers) | |
println(answer1) | |
val answer2 = solve2(numbers) | |
println(answer2) | |
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