Day 24, 2022

go/2022/day24/input.txt

@@ -0,0 +1,27 @@
+#.########################################################################################################################
+#>v<^^><<>^>^>v<>>^^.v>^vv<^v<v><vv.^^^^v<v<v><<^v.<>^^^>>>>><^<.vvvvv.^v>vv<>v<v<^>^v<^v.<>>v<><v^v>.v>^vv^>><v>v>.^>><>#
+#<.v<v>>>.>>>>^<vv><^^v>>v>^><v^>^<.<v^<>>><v<vv<<^^<^^v^<.>v.v>>.v<^><v<v<>^><^>^>><.<<<<^>^^^v.v.>v><^<^v^>.>^>>vv.v^<<#
+#<<>v>^<<^v^<<<vv.>^^>^^v^>>v<>v>v<><^^v<^>><^<>^^v^vv<v<<<>^v^v<.<^>^<>>>.<><<<v<v<<<vv<>>v.^^<v.vv<^<^><^<vv^v<v<v>v.^<#
+#.v^v<v<>>>.v^vv<<v^<vv<<vvv^>^^v.v^v^^v<>^^^^^><.v^v>>v>>^>vvv^^<<^>^v^.v<^<<^v^v>>vv.<<^<<v<v>>^v>^>v.v^><><vvv^>v<>^<<#
+#<v<^<v<^<>v>>v^>>^<<>>v.^^<>vv^<><.v^>><<^<v><<^>>^^^<vv>^<v>.>><<.v^v^<v>^<v>>>>vvv<><^><<<v>v>v.^<<.<v^<>vv<v<<>v>^>v>#
+#.^.<>v>v^v<v>>v<>v>vv<.^><^v<<><>^.^>>v<^v.v^^^^<vv>^<vv^>vv^>^.<>.<^^v<>><^^^.><^v>v^^<>v>>v><>>v.^^<>>v<<^<^<v<vv.>^<<#
+#>^v^>^v>...^<>^.<v>.v<v<>^^v<<<^.v>v>^.><<.v<v<>.>v>>v>>><<v<><^.v>.>>>^>^>.v<>>>v<^^>^v<<^v>^v^<v.v>><>><vvv^v>v^v<v<<<#
+#<^.vv><<><>v^^<^.<^<><..v.^vv<v.vvv><v<^v>v<^v>v^v^^^^<>^^^.^^^v^v>>v^>><>v>^<>v^^.^<^^<v>>v^vvvv>>v^><^<<>>>^<<^v^^<<><#
+#<>><^<^<<^v^>>>v<.>..v>.^>>^v^<<v^<<vv<^v^><<.><^^><.vvv^>>.>>^<^vv><.v>^^>>>.>^vv<^<<>vv<>vv^^^v.>>>><..v>.^<^v<>v.<vv<#
+#<<.<><>.<^<<<<^>^<>^vv^>^>^>vv>>v>>v^>.^.>vv<><.v><<>>vvv.v^^vv>>>v<v<><^<^<>^.v<^^>^><.>>^^^^^vv<<^>^<<v<^v^<.v<<v<<.<<#
+#>>v>.^.<><>^.vvv<vv>^>.^^.v>^v.v>^<vv^v>v>^v^vv<<>><v.<><<v><>^<^<v<>.<^<^^<>^<>>v^v.^<v^^<v^>v<<^.^>>^v>^^^>vv.v.>^v>^>#
+#>^<>v^^^v<v^vv>>v.^>>>^v>><>^v^><v^.v><<>>><^<<.<>v<><><^v^>^^<^^>>^v^>^>^vv^<>>>^v^<.v^^^v<v<v...>^>^<^^v<v^^v>^^>.<^^>#
+#<v<v^^v<>><<<^vvv<vv>>.^.<>>.^v^^<>>v^^>v><>v><v<^^.v^>>.vv^v><>^^v<>>^>^<<^.>v<v^vvv^.><<<v.^^<vvv^<.>>^.<<vv^<<<>.^>><#
+#>.>^.v.>>^<v><><^<.>^v<><>v^^<.>vvv<><>.<v<>.><<.^v^^v^.>vvvv^>.<>><<^v<<>^<<<><<>>^<^>^v<^v<>v^>v<v<.>^<^vv<>^<^>>^>^<<#
+#<.^.>^vv<><>^^<^<.<>vv.>^<<<>v><.<<v<>^<>>v<^^<v^v^^>v<v<^<vv<.v^<>v<^>>.<>^<^.vv><.><v<^<<^<<>^<>v<vvv^v^^>><v>v>..v<<>#
+#<^v>><<v.^^.<^>^<^vvv.^v^v<>vv^v<^vvvvvv^v><>>.^<<^v>v.v.>.^<<^^>>>v^><v^>>>.v^^>.>><^.^^.>.>v^<v^>^<<v<<^><>v<^^>^<v<v<#
+#.v><v>>>v^>^^v<>^<<>>^<v>^><<v^><^.<<v<vv<<^v^^><>><^^><><^^^vv>.^>.<v.^v<v<^<<.v.>>>><<<^v<<.<^<>v.^<^<vvv<.v<.v><^>v<>#
+#<v<v^<^v><<^<>^>>>>^^v<>^^>v<v.^^^^^.^<^<<^><<v^><^.><^><v^>.^>v^v>v.><^<^>v<>^>.<>^..<<>^^>^<><^<^..vv>v^^^v>^^<..^.v<>#
+#>v<<v<<<^.^vvv>>v.>v^v>v<><v.^><^v<>^v<v^v<v<.^^.>v>.v>vvvv^>vv^>^^v><v^>>>.<v^>><.<v><<.>>^^v^vvv<vv^^^<^>v^>vv>^>^vv>>#
+#><<v>^>>>>vv<<><>^>^v>^vv^<^v><>v^.<.^.v>^<<^v>v<.^v.>^v<^^^>v^^.^>vv.<v^>>^.><<>>^<<>.>v.v>>^..>><<..v^>><>v<>.<^v.>>^<#
+#.<<^^<.^v>>>>.>^vv<^<<>>>>^v>v<^.v^<^>>v^<^>^^>>v<>^<v^^^^>><^<^^>>v<.<<v.^v<>>.vv^^^<v^^.^v.<>^>^>><><^.vv<v>v>v<^^>.<>#
+#<<<v>.^v>v>v<^^>vv^<vv<vv><v>v<vv<.>vv<^^^<.v<>..^<<<<<^^^>><v^^>>^<<^v^>><.^<^.<^.<v<vv<..^.><<>vv<^<v<v.<>.<<^v<<^>vv<#
+#.>^^.<<>.>>>.<^<>.<<v<^>v>v>v^v^<v>v^<^>^<<>v^^v^v^^^<>^vvv^vv<.^^>.v^<.>>^>vvv^>.v^>v^v^>.^^<v<<vv^^>v>^vvvvv<vvv^<<>>>#
+#<^v^.<<<><^<<v^^^v^^^<^^<<>.^<^v<.>.^^..^v<<^>^.<<>>.<^>v.^<v>.v^^.<vv^^>v^><v^><^.>>>>>^v<v<^vv^^>^v^.^.^^^>v^<.><>^^>>#
+#.v^vv.^v>vv>>v<vv^^v<v>><.<>><^^>^v.vvvv>><^^>v^v>.v^<.<^.<^<^v.><v>^v<<^^<>vv>>>^v^v^<^<^^^>..<><^<^.vv<<<v>v^.^>^<>^><#
+########################################################################################################################.#

go/2022/day24/main.go

@@ -0,0 +1,211 @@
+package main
+
+import (
+	"container/list"
+	_ "embed"
+	"fmt"
+	"github.com/yeurch/advent-of-code/go/ysl"
+	"math"
+	"strings"
+	"time"
+)
+
+//go:embed input.txt
+var inputDay string
+
+type Point struct {
+	x int
+	y int
+}
+
+func (p *Point) Add(other Point) Point {
+	return Point{p.x + other.x, p.y + other.y}
+}
+
+type GameState struct {
+	*Point
+	n int
+}
+type Blizzard struct {
+	*Point
+	direction Point // used as a 2D vector
+}
+
+type Valley struct {
+	entry  Point
+	exit   Point
+	width  int
+	height int
+
+	spacesCache []ysl.Set[Point]
+	blizzards   []Blizzard
+}
+
+func (v *Valley) GetSpacesAfterN(n int) ysl.Set[Point] {
+	if len(v.spacesCache) > n {
+		return v.spacesCache[n]
+	}
+
+	for i := len(v.spacesCache); i <= n; i++ {
+		v.spacesCache = append(v.spacesCache, v.SimulateMove())
+	}
+	return v.spacesCache[n]
+}
+
+// Returns a set of free spaces after simulating another move
+func (v *Valley) SimulateMove() ysl.Set[Point] {
+	for i := 0; i < len(v.blizzards); i++ {
+		b := &v.blizzards[i]
+		b.x += b.direction.x
+		b.y += b.direction.y
+		if b.x < 0 {
+			b.x = v.width - 1
+		} else if b.x >= v.width {
+			b.x = 0
+		}
+		if b.y < 0 {
+			b.y = v.height - 1
+		} else if b.y >= v.height {
+			b.y = 0
+		}
+	}
+
+	spaces := ysl.NewSet[Point]()
+	for y := 0; y < v.height; y++ {
+		for x := 0; x < v.width; x++ {
+			spaces.Add(Point{x, y})
+		}
+	}
+	for i := 0; i < len(v.blizzards); i++ {
+		b := &v.blizzards[i]
+		spaces.Remove(Point{b.x, b.y})
+	}
+	return spaces
+}
+
+func Part1(input string) int {
+	valley := parseInput(input)
+	return solve(&valley, valley.entry, valley.exit, 0)
+}
+
+func Part2(input string) int {
+	valley := parseInput(input)
+	timeTaken := solve(&valley, valley.entry, valley.exit, 0)
+	timeTaken = solve(&valley, valley.exit, valley.entry, timeTaken)
+	timeTaken = solve(&valley, valley.entry, valley.exit, timeTaken)
+	return timeTaken
+}
+
+func solve(valley *Valley, start Point, end Point, startTimeOffset int) int {
+	routeQueue := list.New()
+	routeQueue.PushBack(GameState{&start, startTimeOffset})
+	//visited := ysl.NewSet[GameState]()
+	visited := ysl.NewSet[string]()
+
+	bestPathLen := math.MaxInt
+	for el := routeQueue.Front(); el != nil; el = el.Next() {
+		gameState := el.Value.(GameState)
+
+		//dupeDetectionState := GameState{gameState.Point, gameState.n % (valley.width * valley.height)}
+		dupeDetectionState := fmt.Sprintf("%d:%d:%d", gameState.x, gameState.y, gameState.n%(valley.width*valley.height))
+		if visited.Contains(dupeDetectionState) {
+			continue
+		}
+		visited.Add(dupeDetectionState)
+
+		if gameState.n >= bestPathLen {
+			continue // We already have a better solution
+		}
+
+		if *gameState.Point == end {
+			if gameState.n < bestPathLen {
+				bestPathLen = gameState.n
+			}
+			continue
+		}
+
+		spaces := valley.GetSpacesAfterN(gameState.n + 1)
+		for dy := -1; dy <= 1; dy++ {
+			for dx := -1; dx <= 1; dx++ {
+				if ysl.Abs(dy)+ysl.Abs(dx) == 2 {
+					continue // eliminate diagonal moves
+				}
+				candidatePos := gameState.Point.Add(Point{dx, dy})
+				if spaces.Contains(candidatePos) || candidatePos == valley.exit || candidatePos == valley.entry {
+					routeQueue.PushBack(GameState{&candidatePos, gameState.n + 1})
+				}
+			}
+		}
+	}
+	return bestPathLen
+}
+
+func parseInput(input string) Valley {
+	lines := strings.Split(strings.TrimSuffix(input, "\n"), "\n")
+
+	var entry, exit Point
+	entryRow := lines[0]
+	width := len(entryRow) - 2
+	height := len(lines) - 2
+	for x := 0; x < width; x++ {
+		if entryRow[x+1] == '.' {
+			entry = Point{x, len(lines) - 2}
+			break
+		}
+	}
+	exitRow := lines[len(lines)-1]
+	for x := 0; x < width; x++ {
+		if exitRow[x+1] == '.' {
+			exit = Point{x, -1}
+			break
+		}
+	}
+
+	directions := map[uint8]Point{
+		'>': {1, 0},
+		'<': {-1, 0},
+		'^': {0, 1},
+		'v': {0, -1},
+	}
+
+	blizzards := make([]Blizzard, 0)
+	for i := 1; i < len(lines)-1; i++ {
+		line := lines[i]
+		y := len(lines) - i - 2
+		for j := 1; j < len(line)-1; j++ {
+			if line[j] == '.' {
+				continue
+			}
+			x := j - 1
+			blizVec := directions[line[j]]
+			blizzards = append(blizzards, Blizzard{&Point{x, y}, blizVec})
+		}
+	}
+
+	spaces := ysl.NewSet[Point]()
+	for y := 0; y < height; y++ {
+		for x := 0; x < width; x++ {
+			spaces.Add(Point{x, y})
+		}
+	}
+	for i := 0; i < len(blizzards); i++ {
+		b := blizzards[i]
+		spaces.Remove(Point{b.x, b.y})
+	}
+	spacesCache := []ysl.Set[Point]{spaces}
+	return Valley{
+		entry, exit, width, height, spacesCache, blizzards,
+	}
+}
+
+func main() {
+	fmt.Println("*** Advent of Code 2022, day 24 ***")
+
+	start := time.Now()
+	fmt.Println("part1: ", Part1(inputDay))
+	fmt.Println(time.Since(start))
+
+	start = time.Now()
+	fmt.Println("part2: ", Part2(inputDay))
+	fmt.Println(time.Since(start))
+}

go/ysl/set.go

@@ -4,6 +4,7 @@ type Set[T comparable] interface {
 	Cardinality() int
 	Contains(item T) bool
 	Add(item T) bool
+	Remove(item T) bool
 	Pop() (T, bool)
 	Intersect(other Set[T]) Set[T]
 }
@@ -39,6 +40,14 @@ func (s *set[T]) Add(item T) bool {
 	return true
 }
 
+func (s *set[T]) Remove(item T) bool {
+	if _, ok := (*s)[item]; !ok {
+		return false
+	}
+	delete(*s, item)
+	return true
+}
+
 func (s *set[T]) Pop() (v T, ok bool) {
 	for k := range *s {
 		delete(*s, k)