package adventofcode2023

import java.io.File

import java.util.PriorityQueue

object Day17 {

private val inputs = File("resources/adventofcode2023/Day17.txt")

.readLines()

.map { line ->

line.toList().map { it.digitToInt() }

}

private fun dijkstra(destinationX: Int, destinationY: Int): Int {

data class Location(val x: Int, val y: Int, val distance: Int)

fun getNeighbors(x: Int, y: Int, distance: Int): Set<Location> {

val neighbors = mutableSetOf<Location>()

if (x > 0) neighbors.add(Location(x - 1, y, distance + inputs[y][x - 1]))

if (y > 0) neighbors.add(Location(x, y - 1, distance + inputs[y - 1][x]))

if (x < inputs[0].size - 1) neighbors.add(Location(x + 1, y, distance + inputs[y][x + 1]))

if (y < inputs.size - 1) neighbors.add(Location(x, y + 1, distance + inputs[y + 1][x]))

return neighbors

}

val frontier = PriorityQueue<Location> { loc1, loc2 -> loc1.distance - loc2.distance }

frontier.add(Location(0, 0, 0))

val minDistances = Array(inputs[0].size) {Array<Int?>(inputs.size) { null } }

minDistances[0][0] = 0

while (frontier.isNotEmpty()) {

val current = frontier.remove()

if (current.x == destinationX && current.y == destinationY) return current.distance

getNeighbors(current.x, current.y, current.distance).forEach { neighbor ->

if (minDistances[neighbor.x][neighbor.y] == null || minDistances[neighbor.x][neighbor.y]!! > neighbor.distance) {

frontier.add(neighbor)

minDistances[neighbor.x][neighbor.y] = neighbor.distance

}

}

}

throw Exception("Location not found")

}

fun part1() = println(dijkstra(inputs[0].size - 1, inputs.size - 1))

}

fun main() {

Day17.part1()

}