73 lines
2 KiB
Swift
73 lines
2 KiB
Swift
|
import Foundation
|
||
|
|
import RegexBuilder
|
||
|
|
|
||
|
|
struct Room {
|
||
|
|
var name: String
|
||
|
|
var flowRate: Int
|
||
|
|
var connections: [String]
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
let regex = #/Valve (?<room>[A-Z]{2}) has flow rate=(?<flow>\d+); tunnels? leads? to valves? (?<links>[A-Z]{2}(, [A-Z]{2})*)/#
|
||
|
|
|
||
|
|
var rooms: [String: Room] = [:]
|
||
|
|
|
||
|
|
for try await line in URL(fileURLWithPath: "day16.input").lines {
|
||
|
|
guard let match = try regex.wholeMatch(in: line) else {
|
||
|
|
fatalError("Invalid input: \(line)")
|
||
|
|
}
|
||
|
|
|
||
|
|
rooms[String(match.room)] = Room(name: String(match.room), flowRate: Int(match.flow)!, connections: match.links.split(separator: ", ").map(String.init))
|
||
|
|
}
|
||
|
|
|
||
|
|
|
||
|
|
struct Path {
|
||
|
|
var rooms: [String] = []
|
||
|
|
var opened: Set<String> = []
|
||
|
|
var pressure: Int = 0
|
||
|
|
}
|
||
|
|
|
||
|
|
let totalTime = 30
|
||
|
|
|
||
|
|
func findPath(from room: Room, previous: String? = nil, time: Int = totalTime, path: inout Path) {
|
||
|
|
guard time > 0 else { return }
|
||
|
|
|
||
|
|
let best = findBest(path: path, room: room, previous: previous, turnedOn: false, time: time - 1)
|
||
|
|
|
||
|
|
if time >= 2, room.flowRate > 0 && path.opened.insert(room.name).inserted {
|
||
|
|
path.pressure += (time - 1) * room.flowRate
|
||
|
|
path = findBest(path: path, room: room, previous: previous, turnedOn: true, time: time - 2)
|
||
|
|
}
|
||
|
|
|
||
|
|
if best.pressure > path.pressure {
|
||
|
|
path = best
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
func findBest(path: Path, room: Room, previous: String? = nil, turnedOn: Bool, time: Int) -> Path {
|
||
|
|
var path = path
|
||
|
|
path.rooms.append("\(room.name)[\(room.flowRate)]\(turnedOn ? "*" : "")")
|
||
|
|
|
||
|
|
var best = path
|
||
|
|
|
||
|
|
for next in room.connections {
|
||
|
|
if !turnedOn && previous == next {
|
||
|
|
continue
|
||
|
|
}
|
||
|
|
|
||
|
|
let nextRoom = rooms[next]!
|
||
|
|
|
||
|
|
var nextPath = path
|
||
|
|
findPath(from: nextRoom, previous: room.name, time: time, path: &nextPath)
|
||
|
|
if nextPath.pressure > best.pressure {
|
||
|
|
best = nextPath
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
return best
|
||
|
|
}
|
||
|
|
|
||
|
|
var path = Path()
|
||
|
|
findPath(from: rooms["AA"]!, path: &path)
|
||
|
|
print(path.rooms)
|
||
|
|
print(path.pressure)
|