advent-of-code/2021
advent-of-code/2021
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day(11): refactor some more

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Signed-off-by: Matej Focko <mfocko@redhat.com>
This commit is contained in:
Matej Focko 2021-12-11 21:02:55 +01:00
parent dbc8b26446
commit f4466c9a88
1 changed files with 14 additions and 19 deletions
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33
src/year2021/day11/Day11.kt
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@ -1,7 +1,6 @@
package year2021.day11
import readInput
import kotlin.collections.ArrayDeque
fun validAdjacentIndices(input: List<List<Int>>, y0: Int, x0: Int): Iterable<Pair<Int, Int>> =
(y0 - 1..y0 + 1)
@ -10,22 +9,20 @@ fun validAdjacentIndices(input: List<List<Int>>, y0: Int, x0: Int): Iterable<Pai
(y != y0 || x != x0) && (y >= 0 && y < input.size) && (x >= 0 && x < input[y].size)
}
fun getFlashes(octopuses: MutableList<MutableList<Int>>): List<Pair<Int, Int>> =
(octopuses.indices)
.flatMap { y -> octopuses[y].indices.map { x -> Pair(y, x) } }
.filter { (y, x) -> octopuses[y][x] > 9 }
.toList()
fun allIndices(octopuses: List<List<Int>>): Iterable<Pair<Int, Int>> =
octopuses.indices.flatMap { y -> octopuses[y].indices.map { x -> y to x } }
fun step(octopuses: MutableList<MutableList<Int>>): Int {
fun getFlashes(octopuses: List<List<Int>>): Iterable<Pair<Int, Int>> =
allIndices(octopuses).filter { (y, x) -> octopuses[y][x] > 9 }
fun step(octopuses: List<MutableList<Int>>): Int {
// First, the energy level of each octopus increases by 1.
for (y in octopuses.indices) {
for (x in octopuses.indices) {
octopuses[y][x]++
}
for ((y, x) in allIndices(octopuses)) {
octopuses[y][x]++
}
// Then, any octopus with an energy level greater than 9 flashes.
val queue = ArrayDeque(getFlashes(octopuses))
val queue = ArrayDeque(getFlashes(octopuses).toList())
while (queue.isNotEmpty()) {
val (y, x) = queue.removeFirst()
@ -43,11 +40,9 @@ fun step(octopuses: MutableList<MutableList<Int>>): Int {
val flashes = octopuses.sumOf { row -> row.count { it > 9 } }
// Reset energy level.
for (y in octopuses.indices) {
for (x in octopuses.indices) {
if (octopuses[y][x] > 9) {
octopuses[y][x] = 0
}
for ((y, x) in allIndices(octopuses)) {
if (octopuses[y][x] > 9) {
octopuses[y][x] = 0
}
}
@ -55,12 +50,12 @@ fun step(octopuses: MutableList<MutableList<Int>>): Int {
}
fun part1(input: List<List<Int>>): Int {
val octopuses = input.map { row -> row.toMutableList() }.toMutableList()
val octopuses = input.map { row -> row.toMutableList() }
return (1..100).sumOf { step(octopuses) }
}
fun part2(input: List<List<Int>>): Int {
val octopuses = input.map { row -> row.toMutableList() }.toMutableList()
val octopuses = input.map { row -> row.toMutableList() }
val count = octopuses.size * octopuses[0].size
return (1..Int.MAX_VALUE).first { step(octopuses) == count }
}