99 lines
2.7 KiB
Swift
99 lines
2.7 KiB
Swift
@main
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struct Day12: Puzzle {
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func run() {
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let rooms = input.reduce(into: Set<String>()) { partialResult, pair in
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partialResult.insert(pair.0)
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partialResult.insert(pair.1)
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}.sorted()
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let small = Set(rooms.enumerated().compactMap { $0.element.first!.isLowercase ? $0.offset : nil })
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let matrix = buildMatrix(rooms, small: small)
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let startIndex = rooms.firstIndex(of: "start")!
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let endIndex = rooms.firstIndex(of: "end")!
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let paths = matrix.findPaths(from: startIndex, to: endIndex, continuing: Path())
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print("total paths", paths.count)
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}
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struct Path {
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var rooms: [Int] = []
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}
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struct Matrix {
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var data: [Bool]
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let size: Int
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let small: Set<Int>
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func neighbors(of index: Int) -> [Int] {
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let slice = data[index * size ..< (index + 1) * size]
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return slice.enumerated().compactMap { $0.element ? $0.offset : nil }
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}
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func findPaths(from: Int, to: Int, continuing: Path) -> [Path] {
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guard from != to else {
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return [continuing]
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}
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var current = continuing
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current.rooms.append(from)
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var result: [Path] = []
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for next in neighbors(of: from) {
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if small.contains(next) && current.rooms.contains(next) {
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continue
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}
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let nextPaths = findPaths(from: next, to: to, continuing: current)
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result.append(contentsOf: nextPaths)
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}
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return result
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}
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}
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func buildMatrix(_ rooms: [String], small: Set<Int>) -> Matrix {
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let count = rooms.count
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var matrix = [Bool](repeating: false, count: count * count)
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for (from, to) in input {
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let fromIndex = rooms.firstIndex(of: from)!
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let toIndex = rooms.firstIndex(of: to)!
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matrix[fromIndex + count * toIndex] = true
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matrix[toIndex + count * fromIndex] = true
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}
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return Matrix(data: matrix, size: count, small: small)
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}
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let input: [(String, String)] = [
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("rf", "RL"),
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("rf", "wz"),
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("wz", "RL"),
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("AV", "mh"),
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("end", "wz"),
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("end", "dm"),
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("wz", "gy"),
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("wz", "dm"),
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("cg", "AV"),
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("rf", "AV"),
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("rf", "gy"),
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("end", "mh"),
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("cg", "gy"),
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("cg", "RL"),
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("gy", "RL"),
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("VI", "gy"),
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("AV", "gy"),
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("dm", "rf"),
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("start", "cg"),
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("start", "RL"),
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("rf", "mh"),
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("AV", "start"),
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("qk", "mh"),
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("wz", "mh"),
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]
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}
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