advent-of-code/2018/07/main_2.kt

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Kotlin
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2018-12-07 16:24:22 +01:00
import java.io.File
import java.io.InputStream
import kotlin.math.max
fun main(args: Array<String>) {
val numWorkers = 5
val inputStream = File("input").inputStream()
val inputLines = inputStream.bufferedReader().use { it.readText() }.split("\n")
var map: HashMap<Char, HashSet<Char>> = HashMap()
for (line in inputLines) {
val step = line[36]
val dep = line[5]
// Make sure values that are only referenced as dependencies
// (i. e. the first step in our chain) are also added to the set.
map.getOrPut(dep, { HashSet<Char>() })
val currentDeps = map.getOrPut(step, { HashSet<Char>() })
currentDeps.add(dep)
}
var workers = MutableList<Pair<Char, Int>>(numWorkers, { Pair( ' ', 0 ) })
var timer = 0
// While there are still objects to be processed or at least one worker is still working
while (map.size > 0 || true in workers.map{ w -> w.second > 0 }) {
// Only remove the element from dependencies once it’s been worked on
for (worker in workers) {
if (worker.second == 0) {
map.values.map{ v -> v.remove(worker.first) }
}
}
while (map.size > 0 && 0 in workers.map{ w -> w.second }) {
// The keyset in Kotlin is already sorted, so we can just take the first value
val candidates = map.entries.map{ e -> Pair(e.key, e.value.size) }.filter{ e -> e.second == 0 }.map{ e -> e.first }
if (candidates.size == 0) {
break
}
val next = candidates[0]
val currentWorker = workers.indexOf(workers.find{ w -> w.second == 0 })
// The char 'A' is 65, but we want 60 + its position in the alphabet
workers[currentWorker] = Pair(next, next.toInt() - 4)
map.remove(next)
}
timer++
workers = workers.map{ w -> Pair(w.first, max(0, w.second - 1)) }.toMutableList()
}
println(timer)
}