77 lines
2.5 KiB
Swift
77 lines
2.5 KiB
Swift
import Foundation
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struct Coord : Hashable, CustomStringConvertible {
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let (x, y): (Int, Int)
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var description: String { return "(\(x),\(y))" }
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}
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func readInput(_ fileName: String) throws -> [Coord] {
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let xy = try Regex(#"([0-9]+),([0-9]+)"#)
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return try String(contentsOfFile: fileName, encoding: .ascii)
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.split(separator: "\n")
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.compactMap { $0.wholeMatch(of: xy) }
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.map { Coord(
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x: Int($0.output[1].substring!)!,
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y: Int($0.output[2].substring!)!
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) }
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}
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struct Map : CustomStringConvertible {
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let walls: Set<Coord>
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let (w, h): (Int, Int)
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var description: String {
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let top = " \u{001B}[4m" + (0..<w).map { " \($0 % 10)" }.joined() + "\u{001B}[0m\n"
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let maze = (0..<h).map { i in
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String(format: "%2d▕", i) + (0..<w).map { j in
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walls.contains(Coord(x: j, y: i)) ? "██" : " "
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}.joined() + "▌"
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}.joined(separator: "\n")
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let bot = "\n " + String(repeating: "🬂", count: w*2) + "🬀"
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return top + maze + bot
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}
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func dijkstra(from start: Coord, to end: Coord) -> Int? {
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var q = Heap<(Coord, Int)>(comparator: { l, r in l.1 < r.1 })
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var seen: Set<Coord> = [start]
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q.insert((start, 0))
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while let (cell, cost) = q.pop() {
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if cell == end {
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return cost
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}
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[(0, -1), (0, 1), (-1, 0), (1, 0)].map { dy, dx in
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Coord(x: cell.x + dx, y: cell.y + dy)}
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.filter { c in c.x >= 0 && c.y >= 0 && c.x < w && c.y < h }
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.filter { !seen.contains($0) }
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.filter { !walls.contains($0) }
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.forEach { neighbor in
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seen.insert(neighbor)
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q.insert((neighbor, cost + 1))
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}
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}
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return nil
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}
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}
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@main
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struct AoC {
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static func main() throws {
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let bytes = try readInput(CommandLine.arguments[1])
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let w = Int(CommandLine.arguments[2]) ?? 71
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let h = Int(CommandLine.arguments[3]) ?? 71
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for limit in 1024..<bytes.count {
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let map = Map(walls: Set(bytes.prefix(limit)), w: w, h: h)
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if let cost = map.dijkstra(
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from: Coord(x: 0, y: 0),
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to: Coord(x: map.w - 1, y: map.h - 1)
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) {
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print("\(limit): \(cost)")
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} else {
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print(map)
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print("found byte \(limit-1): \(bytes[limit-1])")
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return
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}
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}
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}
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}
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