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MatsemannMatsemann
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aoc2023 day 16 + 17, added dijkstra util
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‎adventofcode2023/src/main/kotlin/com/matsemann/adventofcode2023/Day16.kt‎

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package com.matsemann.adventofcode2023
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import com.matsemann.adventofcode2023.utils.*
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import com.matsemann.adventofcode2023.utils.Direction.*
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fun day16_1(lines: List<String>): Any {
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val grid = lines.map { it.toList() }
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val bounds = grid.bounds()
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val res = generateSequence { }.scan(
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listOf(
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IntVec(
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0,
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0
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) to RIGHT
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) to setOf<Pair<IntVec, Direction>>()
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) { (beams, seenStates), _ ->
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val newBeams = beams.flatMap { (pos, dir) ->
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if (!pos.withinBounds(bounds) || (pos to dir) in seenStates) {
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emptyList()
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} else {
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val value = grid[pos]
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when {
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value == '|' && dir in listOf(LEFT, RIGHT) -> listOf((pos + DOWN) to DOWN, (pos + UP) to UP)
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value == '-' && dir in listOf(DOWN, UP) -> listOf((pos + LEFT) to LEFT, (pos + RIGHT) to RIGHT)
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value == '/' && dir == RIGHT -> listOf((pos + UP) to UP)
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value == '/' && dir == DOWN -> listOf((pos + LEFT) to LEFT)
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value == '/' && dir == LEFT -> listOf((pos + DOWN) to DOWN)
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value == '/' && dir == UP -> listOf((pos + RIGHT) to RIGHT)
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value == '\\' && dir == RIGHT -> listOf((pos + DOWN) to DOWN)
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value == '\\' && dir == DOWN -> listOf((pos + RIGHT) to RIGHT)
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value == '\\' && dir == LEFT -> listOf((pos + UP) to UP)
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value == '\\' && dir == UP -> listOf((pos + LEFT) to LEFT)
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else -> listOf((pos + dir) to dir)
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}
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}
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}
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newBeams to (seenStates + beams)
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}.dropWhile { (beams, seenStates) -> beams.isNotEmpty() }.first()
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val seenPos = res.second.map { it.first }.filter { it.withinBounds(bounds) }
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// println(seenPos.showAsGrid())
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return seenPos.toSet().size
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}
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fun day16_2(lines: List<String>): Any {
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val grid = lines.map { it.toList() }
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val bounds = grid.bounds()
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val vertical = (0..bounds.y).flatMap { y -> listOf(IntVec(0, y) to RIGHT, IntVec(bounds.x, y) to LEFT) }
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val horizontal = (0..bounds.x).flatMap { x -> listOf(IntVec(x, 0) to DOWN, IntVec(x, bounds.y) to UP) }
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return (vertical + horizontal).maxOf { startPos ->
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generateSequence { }.scan(listOf(startPos) to setOf<Pair<IntVec, Direction>>()) { (beams, seenStates), _ ->
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val newBeams = beams.flatMap { (pos, dir) ->
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if (!pos.withinBounds(bounds) || (pos to dir) in seenStates) {
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emptyList()
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} else {
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val value = grid[pos]
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when {
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value == '|' && dir in listOf(LEFT, RIGHT) -> listOf((pos + DOWN) to DOWN, (pos + UP) to UP)
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value == '-' && dir in listOf(DOWN, UP) -> listOf(
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(pos + LEFT) to LEFT,
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(pos + RIGHT) to RIGHT
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)
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value == '/' && dir == RIGHT -> listOf((pos + UP) to UP)
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value == '/' && dir == DOWN -> listOf((pos + LEFT) to LEFT)
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value == '/' && dir == LEFT -> listOf((pos + DOWN) to DOWN)
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value == '/' && dir == UP -> listOf((pos + RIGHT) to RIGHT)
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value == '\\' && dir == RIGHT -> listOf((pos + DOWN) to DOWN)
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value == '\\' && dir == DOWN -> listOf((pos + RIGHT) to RIGHT)
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value == '\\' && dir == LEFT -> listOf((pos + UP) to UP)
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value == '\\' && dir == UP -> listOf((pos + LEFT) to LEFT)
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else -> listOf((pos + dir) to dir)
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}
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}
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}
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newBeams to (seenStates + beams)
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}.dropWhile { (beams, seenStates) -> beams.isNotEmpty() }
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.first().second
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.map { it.first }.filter { it.withinBounds(bounds) }.toSet()
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.size
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}
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}
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fun main() {
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Direction.setYDown()
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val a = generateSequence { }.runningFold(0) { acc, _ ->
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acc + 1
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}.dropWhile { it < 8 }.take(5).toList()
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println(a)
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// run("1", fileName = "day16_ex.txt", func = ::day16_1)
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// run("2", fileName = "day16_ex.txt", func = ::day16_2)
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// run("1", fileName = "day16.txt", func = ::day16_1)
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// run("2", fileName = "day16.txt", func = ::day16_2)
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}

‎adventofcode2023/src/main/kotlin/com/matsemann/adventofcode2023/Day17.kt‎

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package com.matsemann.adventofcode2023
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import com.matsemann.adventofcode2023.utils.*
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import com.matsemann.adventofcode2023.utils.IntVec.Companion.showAsGrid
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fun day17_1(lines: List<String>): Any {
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val grid = lines.map { it.toList().map { it.digitToInt().toLong() } }
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val bounds = grid.bounds()
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data class State(val pos: IntVec, val dir: Direction, val straights: Int)
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val dijkstra = Dijkstra<State> {(pos, dir, straights) ->
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val straight = if (straights < 3 && (pos+dir).withinBounds(bounds)) {
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State(pos + dir, dir, straights + 1) to grid[pos+dir]
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} else {
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null
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}
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val leftDir = dir.turnCcw()
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val left = if ((pos+leftDir).withinBounds(bounds)) {
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State(pos + leftDir, leftDir, 1) to grid[pos+leftDir]
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} else {
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null
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}
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val rightDir = dir.turnCw()
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val right = if ((pos+rightDir).withinBounds(bounds)) {
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State(pos + rightDir, rightDir, 1) to grid[pos+rightDir]
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} else {
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null
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}
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listOfNotNull(straight, left, right)
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}
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val res = dijkstra.solve(State(IntVec(0,0), Direction.RIGHT, 0)) { (pos, dir, straights) ->
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pos == bounds
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}
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val path = dijkstra.path(res!!.first)
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val cost = path.map { grid[it.pos] }.sum() - grid[IntVec(0,0)]
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return cost
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}
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fun day17_2(lines: List<String>): Any {
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val grid = lines.map { it.toList().map { it.digitToInt().toLong() } }
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val bounds = grid.bounds()
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data class State(val pos: IntVec, val dir: Direction, val straights: Int)
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val dijkstra = Dijkstra<State> {(pos, dir, straights) ->
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val straight = if (straights < 10 && (pos+dir).withinBounds(bounds)) {
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State(pos + dir, dir, straights + 1) to grid[pos+dir]
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} else {
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null
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}
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val leftDir = dir.turnCcw()
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val left = if (straights > 3 && (pos+leftDir).withinBounds(bounds)) {
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State(pos + leftDir, leftDir, 1) to grid[pos+leftDir]
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} else {
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null
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}
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val rightDir = dir.turnCw()
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val right = if (straights > 3 && (pos+rightDir).withinBounds(bounds)) {
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State(pos + rightDir, rightDir, 1) to grid[pos+rightDir]
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} else {
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null
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}
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listOfNotNull(straight, left, right)
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}
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// Now start direction matters, but simpler to just try UP and RIGHT
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// and see which one is shorter, than adding support for two start nodes in my
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// Dijkstra
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val res = dijkstra.solve(State(IntVec(0,0), Direction.UP, 0)) { (pos, dir, straights) ->
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pos == bounds && straights > 3
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}
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val path = dijkstra.path(res!!.first)
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println(path.map { it.pos }.showAsGrid())
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return path.map { grid[it.pos] }.sum() - grid[IntVec(0,0)]
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}
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fun main() {
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// run("1", fileName = "day17_ex.txt", func = ::day17_1)
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run("2", fileName = "day17_ex.txt", func = ::day17_2)
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run("2", fileName = "day17_ex2.txt", func = ::day17_2)
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// run("1", fileName = "day17.txt", func = ::day17_1)
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// 1304 too high
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run("2", fileName = "day17.txt", func = ::day17_2)
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}

‎adventofcode2023/src/main/kotlin/com/matsemann/adventofcode2023/utils/GraphUtils.kt‎

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@@ -29,7 +29,6 @@ class DirectedGraph() : Graph {
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}
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}
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32-
class Dijkstra() {}
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class AStar() {}
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class FloydWarshall() {}
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‎adventofcode2023/src/main/kotlin/com/matsemann/adventofcode2023/utils/SearchUtils.kt‎

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package com.matsemann.adventofcode2023.utils
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import java.util.PriorityQueue
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/**
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* A general breadth first search, where you
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* can pass in the neighbor generating function,
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}
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class Dijkstra<E>(val neighborFunc: Dijkstra<E>.(E) -> Iterable<Pair<E, Long>>) {
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val Q = PriorityQueue<Pair<E, Long>>(compareBy { it.second })
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val visited = mutableSetOf<E>()
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val seen = mutableSetOf<E>()
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var endFound: Pair<E, Long>? = null
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var parent = mutableMapOf<E, E>()
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fun clear() {
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Q.clear()
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seen.clear()
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visited.clear()
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parent.clear()
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endFound = null
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}
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/**
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* Runs it, either until it's not possible to go any further,
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* or if provided until the goal function returns true for a node
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*/
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fun solve(start: E, goalFunction: (Dijkstra<E>.(E) -> Boolean)? = null): Pair<E, Long>? {
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clear()
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Q.add(start to 0)
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seen.add(start)
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while (Q.isNotEmpty()) {
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val (currentNode, cost) = Q.remove()
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if (currentNode in visited) {
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continue
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}
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visited += currentNode
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if (goalFunction != null && this.goalFunction(currentNode)) {
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endFound = currentNode to cost
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return endFound
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}
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val neighbors = this.neighborFunc(currentNode)
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neighbors.forEach { (neighbor, neighborCost) ->
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if (neighbor !in visited) {
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val totalCost = cost + neighborCost
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val currentCost = Q.find { it.first == neighbor }?.second ?: Long.MAX_VALUE
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if (totalCost < currentCost) {
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parent[neighbor] = currentNode
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Q.offer(neighbor to totalCost)
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}
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}
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}
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}
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return null
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}
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/**
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* After a solve, returns the path from start to the node
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*/
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fun path(node: E): List<E> {
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val path = mutableListOf<E>()
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var current: E? = node
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while (current != null) {
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path.addFirst(current)
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current = parent[current]
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}
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return path
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}
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}
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73145
fun main() {
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data class Node(val name: String, val neighbors: List<String>)
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val nodes = listOf(
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Node("A", listOf("B", "C")),
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Node("B", listOf("A", "C")),

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