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Partial: Day 18

Signed-off-by: Knut Ahlers <knut@ahlers.me>
This commit is contained in:
Knut Ahlers 2019-12-18 17:46:23 +01:00
parent 84e8a9afa0
commit 2820e2d148
Signed by: luzifer
GPG key ID: DC2729FDD34BE99E
3 changed files with 461 additions and 0 deletions

320
day18.go Normal file
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package aoc2019
import (
"bytes"
"fmt"
"io/ioutil"
"log"
"math"
"sort"
"strings"
"sync"
"github.com/pkg/errors"
)
type day18TileType int
const (
day18TileTypeWall day18TileType = iota
day18TileTypeFloor
day18TileTypeDoor
day18TileTypeKey
day18TileTypeActor
)
type day18Tile struct {
X, Y int
Type day18TileType
KeyLockID string
distFromActor int64
}
func (d *day18Tile) updateBFSDistance(grid day18Grid, dist int64, wg *sync.WaitGroup) {
defer wg.Done()
if d.distFromActor < dist {
// Do not update tiles which dist has been set already
return
}
// Set distance
d.distFromActor = dist
// Seek adjacent tiles and update them too
for _, t := range []*day18Tile{
grid[grid.key(d.X-1, d.Y)],
grid[grid.key(d.X+1, d.Y)],
grid[grid.key(d.X, d.Y-1)],
grid[grid.key(d.X, d.Y+1)],
} {
if t.Type == day18TileTypeWall || t.Type == day18TileTypeDoor {
// Doors and walls are inaccessible objects and therefore
// immediately stop distance progressing
continue
}
wg.Add(1)
go t.updateBFSDistance(grid, dist+1, wg)
}
}
type day18Grid map[string]*day18Tile
func (d day18Grid) accessibleKeys() []string {
var keys []string
for _, key := range d.getTilesByType(day18TileTypeKey) {
if key.distFromActor < math.MaxInt64 {
keys = append(keys, key.KeyLockID)
}
}
sort.Strings(keys)
return keys
}
func (d day18Grid) bounds() (minX, minY, maxX, maxY int) {
minX, minY = math.MaxInt64, math.MaxInt64
for _, t := range d {
if t.X < minX {
minX = t.X
}
if t.Y < minY {
minY = t.Y
}
if t.X > maxX {
maxX = t.X
}
if t.Y > maxY {
maxY = t.Y
}
}
return
}
func (d day18Grid) clone() day18Grid {
var out = make(day18Grid)
for key, tile := range d {
var tmpTile = &day18Tile{}
*tmpTile = *tile
out[key] = tmpTile
}
return out
}
func (d day18Grid) getKeyByID(id string) *day18Tile {
for _, key := range d.getTilesByType(day18TileTypeKey) {
if key.KeyLockID == id {
return key
}
}
return nil
}
func (d day18Grid) getPathDistances(path string, shortest *int64) (map[string]int64, error) {
var (
dist int64
// Always work on a clone and leave the original grid intact
grid = d.clone()
out = make(map[string]int64)
)
grid.updateBFSDistance()
// Apply movements
for _, c := range path {
key := grid.getKeyByID(string(c))
moveDist, err := grid.move(key.X, key.Y)
if err != nil {
return nil, errors.Wrap(err, "Unable to move")
}
dist += moveDist
grid.updateBFSDistance()
if dist >= *shortest {
return nil, nil
}
}
remainingKeys := grid.getTilesByType(day18TileTypeKey)
if len(remainingKeys) == 0 {
fmt.Printf("DBG %s = %d\n", path, dist)
out[path] = dist
if dist < *shortest {
*shortest = dist
}
return out, nil
}
sort.Slice(remainingKeys, func(i, j int) bool { return remainingKeys[i].distFromActor < remainingKeys[j].distFromActor })
for _, k := range remainingKeys {
if k.distFromActor == math.MaxInt64 {
continue
}
recDists, err := d.getPathDistances(path+k.KeyLockID, shortest)
if err != nil {
return nil, err
}
for key, dist := range recDists {
out[key] = dist
}
}
return out, nil
}
func (d day18Grid) getTilesByType(t day18TileType) []*day18Tile {
var out []*day18Tile
for _, tile := range d {
if tile.Type == t {
out = append(out, tile)
}
}
return out
}
func (day18Grid) key(x, y int) string { return fmt.Sprintf("%d:%d", x, y) }
func (d day18Grid) move(x, y int) (int64, error) {
var (
origin = d.getTilesByType(day18TileTypeActor)[0] // There MUST be only one actor
target = d[d.key(x, y)]
)
if target.distFromActor == math.MaxInt64 {
return 0, errors.New("Distance not initialized / move to unreachable destination")
}
if target.Type == day18TileTypeKey {
for _, door := range d.getTilesByType(day18TileTypeDoor) {
if door.KeyLockID == strings.ToUpper(target.KeyLockID) {
// Unlock door, transform to floor
door.Type = day18TileTypeFloor
break
}
}
}
// Move the actor
target.Type = day18TileTypeActor
origin.Type = day18TileTypeFloor
return target.distFromActor, nil
}
func (d day18Grid) print() {
var minX, minY, maxX, maxY = d.bounds()
for y := minY; y <= maxY; y++ {
for x := minX; x <= maxX; x++ {
var t = d[d.key(x, y)]
switch t.Type {
case day18TileTypeActor:
fmt.Print("@")
case day18TileTypeDoor, day18TileTypeKey:
fmt.Print(t.KeyLockID)
case day18TileTypeFloor:
fmt.Print(".")
case day18TileTypeWall:
fmt.Print("\u2588")
}
}
fmt.Println()
}
}
func (d day18Grid) updateBFSDistance() {
// Reset distances
for _, t := range d {
t.distFromActor = math.MaxInt64
}
wg := new(sync.WaitGroup)
wg.Add(1)
d.getTilesByType(day18TileTypeActor)[0].updateBFSDistance(d, 0, wg)
wg.Wait()
}
func day18ReadGrid(raw []byte) day18Grid {
var (
out = make(day18Grid)
x, y int
)
for _, c := range raw {
var t = &day18Tile{X: x, Y: y, KeyLockID: string(c)}
switch {
case c == '\n':
x, y = 0, y+1
continue
case c == '#':
t.Type = day18TileTypeWall
case c == '.':
t.Type = day18TileTypeFloor
case c == '@':
t.Type = day18TileTypeActor
case 'a' <= c && c <= 'z':
t.Type = day18TileTypeKey
case 'A' <= c && c <= 'Z':
t.Type = day18TileTypeDoor
}
out[out.key(x, y)] = t
x++
}
return out
}
func solveDay18Part1(inFile string) (int64, error) {
raw, err := ioutil.ReadFile(inFile)
if err != nil {
return 0, errors.Wrap(err, "Unable to read file")
}
grid := day18ReadGrid(bytes.TrimSpace(raw))
grid.print()
// Calculate max heuristic distance by using always using shortest
// single distance which will not be the shortest total distance
// but set an upper limit for the heuristic
cgrid := grid.clone()
cgrid.updateBFSDistance()
var minDist int64
for len(cgrid.accessibleKeys()) > 0 {
keys := cgrid.getTilesByType(day18TileTypeKey)
sort.Slice(keys, func(i, j int) bool { return keys[i].distFromActor < keys[j].distFromActor })
d, err := cgrid.move(keys[0].X, keys[0].Y)
if err != nil {
return 0, errors.Wrap(err, "Failed to move")
}
minDist += d
cgrid.updateBFSDistance()
}
log.Printf("Shortest distance for heuristic: %d", minDist)
dists, err := grid.getPathDistances("", &minDist)
if err != nil {
return 0, errors.Wrap(err, "Unable to determine distances")
}
fmt.Printf("%#v\n", dists)
return minDist, nil
}
func solveDay18Part2(inFile string) (int64, error) { return 0, errors.New("Not implemented") }

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day18_input.txt Normal file
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#.#.#.#.#.#.#M#############.#.###.#####.#####.###.#.###.#.#.#################.#.#
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#########.#####.#.###########.#.#######.#.###########.#######.#C#####.#.#.#.###.#
#.........#.#.....#.........#.#.#.......#...........#...........#...#.#.#...#...#
#.#########.#.#########.#####.#W###.###############.###.#########.###.#.#####.###
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#################################################################################

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day18_test.go Normal file
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package aoc2019
import (
"math"
"testing"
)
func TestDay18GetDistances(t *testing.T) {
grid := day18ReadGrid([]byte("########################\n#...............b.C.D.f#\n#.######################\n#.....@.a.B.c.d.A.e.F.g#\n########################"))
var maxInt int64 = math.MaxInt64
dists, err := grid.getPathDistances("", &maxInt)
if err != nil {
t.Fatalf("GetPathDistances caused an error: %s", err)
}
if d := dists["bacdfeg"]; d != 132 {
t.Errorf("Invalid distance for bacdfeg: exp=132 got=%d", d)
}
grid = day18ReadGrid([]byte(`#################
#i.G..c...e..H.p#
########.########
#j.A..b...f..D.o#
########@########
#k.E..a...g..B.n#
########.########
#l.F..d...h..C.m#
#################`))
maxInt = math.MaxInt64
dists, err = grid.getPathDistances("", &maxInt)
if err != nil {
t.Fatalf("GetPathDistances caused an error: %s", err)
}
if d := dists["afbjgnhdloepcikm"]; d != 136 {
t.Errorf("Invalid distance for bacdfeg: exp=136 got=%d", d)
}
}
func TestCalculateDay18_Part1(t *testing.T) {
res, err := solveDay18Part1("day18_input.txt")
if err != nil {
t.Fatalf("Day 18 solver failed: %s", err)
}
t.Logf("Solution Day 18 Part 1: %d", res)
}
func TestCalculateDay18_Part2(t *testing.T) {
res, err := solveDay18Part2("day18_input.txt")
if err != nil {
t.Fatalf("Day 18 solver failed: %s", err)
}
t.Logf("Solution Day 18 Part 2: %d", res)
}