adventofcode/2019/day18/main.go

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package main
import (
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"bufio"
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"fmt"
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"io"
"log"
"os"
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helpers "git.bullercodeworks.com/brian/adventofcode/helpers"
)
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type state struct {
Pos helpers.Coordinate3d
Steps int
}
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func main() {
file := "input"
if helpers.GetArgNumber(1) != "" {
file = helpers.GetArgNumber(1)
}
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f, err := os.Open(file)
if err != nil {
log.Fatal(err)
}
defer f.Close()
part := helpers.GetArgNumber(2)
if part != "2" {
part1(f)
} else {
part2(f)
}
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}
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func part1(r io.Reader) {
vault, doors, keys, start, allkeys := readVault(r)
fmt.Println(search(vault, doors, keys, start, allkeys, 0))
}
func part2(r io.Reader) {
vault, doors, keys, start, allKeys := readVault(r)
directions := []helpers.Coordinate{{X: 0, Y: -1}, {X: 1, Y: 0}, {X: 0, Y: 1}, {X: -1, Y: 0}}
vault[start] = false
for _, d := range directions {
vault[helpers.Coordinate{X: start.X + d.X, Y: start.Y + d.Y}] = false
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}
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total := 0
haveKeys := allKeys
for x := 0; x < start.X; x++ {
for y := 0; y < start.Y; y++ {
haveKeys ^= keys[helpers.Coordinate{X: x, Y: y}]
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}
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}
total += search(vault, doors, keys, helpers.Coordinate{X: start.X - 1, Y: start.Y - 1}, allKeys, haveKeys)
haveKeys = allKeys
for x := start.X + 1; x <= start.X*2; x++ {
for y := 0; y < start.Y; y++ {
haveKeys ^= keys[helpers.Coordinate{X: x, Y: y}]
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}
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}
total += search(vault, doors, keys, helpers.Coordinate{X: start.X + 1, Y: start.Y - 1}, allKeys, haveKeys)
haveKeys = allKeys
for x := start.X + 1; x <= start.X*2; x++ {
for y := start.Y + 1; y <= start.Y*2; y++ {
haveKeys ^= keys[helpers.Coordinate{X: x, Y: y}]
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}
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}
total += search(vault, doors, keys, helpers.Coordinate{X: start.X + 1, Y: start.Y + 1}, allKeys, haveKeys)
haveKeys = allKeys
for x := 0; x < start.X; x++ {
for y := start.Y + 1; y <= start.Y*2; y++ {
haveKeys ^= keys[helpers.Coordinate{X: x, Y: y}]
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}
}
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total += search(vault, doors, keys, helpers.Coordinate{X: start.X - 1, Y: start.Y + 1}, allKeys, haveKeys)
fmt.Println(total)
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}
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func readVault(r io.Reader) (map[helpers.Coordinate]bool, map[helpers.Coordinate]int, map[helpers.Coordinate]int, helpers.Coordinate, int) {
scan := bufio.NewScanner(r)
var start helpers.Coordinate
var x, y, allkeys int
v := make(map[helpers.Coordinate]bool)
doors, keys := make(map[helpers.Coordinate]int), make(map[helpers.Coordinate]int)
for scan.Scan() {
x = 0
for _, c := range scan.Text() {
if c != '#' {
v[helpers.Coordinate{X: x, Y: y}] = true
if c == '@' {
start = helpers.Coordinate{X: x, Y: y}
} else if c != '.' {
if c < 'a' {
k := 1 << (c - 'A')
doors[helpers.Coordinate{X: x, Y: y}] = k
allkeys |= k
} else {
k := 1 << (c - 'a')
keys[helpers.Coordinate{X: x, Y: y}] = k
allkeys |= k
}
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}
}
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x++
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}
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y++
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}
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if err := scan.Err(); err != nil {
log.Fatal(err)
}
return v, doors, keys, start, allkeys
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}
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func search(vault map[helpers.Coordinate]bool, doors, keys map[helpers.Coordinate]int, start helpers.Coordinate, allKeys, haveKeys int) int {
directions := []helpers.Coordinate{{X: 0, Y: -1}, {X: 1, Y: 0}, {X: 0, Y: 1}, {X: -1, Y: 0}}
queue, visited := []state{{Pos: helpers.Coordinate3d{X: start.X, Y: start.Y, Z: haveKeys}}}, make(map[helpers.Coordinate3d]bool)
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var st state
for {
st, queue = queue[0], queue[1:]
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if st.Pos.Z&allKeys == allKeys {
return st.Steps
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}
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visited[st.Pos] = true
for _, d := range directions {
next := helpers.Coordinate3d{X: st.Pos.X + d.X, Y: st.Pos.Y + d.Y, Z: st.Pos.Z}
if !vault[helpers.Coordinate{X: next.X, Y: next.Y}] || visited[next] {
continue
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}
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door, ok := doors[helpers.Coordinate{X: next.X, Y: next.Y}]
if ok && next.Z&door != door {
continue
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}
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key, ok := keys[helpers.Coordinate{X: next.X, Y: next.Y}]
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if ok {
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next.Z |= key
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}
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queue = append(queue, state{Pos: next, Steps: st.Steps + 1})
}
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}
}