advent-of-code-2024/day18/part1.kts
2024-12-17 23:47:15 -07:00

62 lines
No EOL
2.4 KiB
Kotlin
Executable file

#!/usr/bin/env kotlin
import java.io.File
import java.util.LinkedList
data class Block (
var type: Type,
var seen: Boolean = false,
var distance: Int = Int.MAX_VALUE
) {
enum class Type {
Empty,
Byte,
}
}
val bytes = File("input.txt").readLines().subList(0, 1024).map { it.split(",").let { s -> s[0].toInt() to s[1].toInt() } }.toSet()
val grid = (0..70).map { row -> (0..70).map { col ->
Block(
type = if (bytes.contains(col to row)) Block.Type.Byte
else Block.Type.Empty,
)
}.toMutableList() }.toMutableList()
grid[0][0].seen = true
grid[0][0].distance = 0
val queue = LinkedList<Pair<Int, Int>>()
queue.addFirst(0 to 0)
while (!queue.isEmpty()) {
// Take one off the queue
val next = queue.pollLast() ?: break
// Check if we reached goal
if (next.first == 70 && next.second == 70) {
break
}
// Add neighbors
if ((0..70).contains(next.first + 1) && grid[next.first + 1][next.second].let { it.type == Block.Type.Empty && it.distance > grid[next.first][next.second].distance + 1 }) {
grid[next.first + 1][next.second].seen = true
grid[next.first + 1][next.second].distance = grid[next.first][next.second].distance + 1
queue.addFirst(next.first + 1 to next.second)
}
if ((0..70).contains(next.second + 1) && grid[next.first][next.second + 1].let { it.type == Block.Type.Empty && it.distance > grid[next.first][next.second].distance + 1 }) {
grid[next.first][next.second + 1].seen = true
grid[next.first][next.second + 1].distance = grid[next.first][next.second].distance + 1
queue.addFirst(next.first to next.second + 1)
}
if ((0..70).contains(next.first - 1) && grid[next.first - 1][next.second].let { it.type == Block.Type.Empty && it.distance > grid[next.first][next.second].distance + 1 }) {
grid[next.first - 1][next.second].seen = true
grid[next.first - 1][next.second].distance = grid[next.first][next.second].distance + 1
queue.addFirst(next.first - 1 to next.second)
}
if ((0..70).contains(next.second - 1) && grid[next.first][next.second - 1].let { it.type == Block.Type.Empty && it.distance > grid[next.first][next.second].distance + 1 }) {
grid[next.first][next.second - 1].seen = true
grid[next.first][next.second - 1].distance = grid[next.first][next.second].distance + 1
queue.addFirst(next.first to next.second - 1)
}
}
println(grid[70][70].distance)