make d19p2 shorter

day19/d19p2.swift

@@ -1,37 +1,24 @@
 import Foundation
 
-enum Color: Character, CustomStringConvertible {
+typealias Color = Character
-    case r = "r"
-    case g = "g"
-    case u = "u"
-    case w = "w"
-    case b = "b"
-    var description: String { return String(self.rawValue) }
-}
 
 func readInput(_ filePath: String) throws -> ([[Color]], [[Color]]) {
     let content = try String(contentsOfFile: filePath, encoding: .ascii)
     let lines = content.split(separator: "\n")
-    let towels = lines[0].split(separator: ", ").map { $0.compactMap(Color.init) }
+    let towels = lines[0].split(separator: ", ").map(Array.init)
-    let patterns = lines[1..<lines.count].map { $0.compactMap(Color.init) }
+    let patterns = lines[1..<lines.count].map(Array.init)
     return (towels, patterns)
 }
 
-var cache: [[Color]: Int] = [:]
+var knowns: [[Color]: Int] = [[]: 1]
 func matches(_ pattern: [Color], _ towels: [[Color]]) -> Int {
-    if pattern.count == 0 {
+    if let cached = knowns[pattern] { return cached }
-        return 1
+    knowns[pattern] = towels
-    }
-    if let cached = cache[pattern] {
-        return cached
-    }
-    let r = towels
         .filter { pattern.starts(with: $0) }
         .map { matches(Array(pattern[$0.count..<pattern.count]), towels) }
         .reduce(0, +)
-    cache[pattern] = r
+    return knowns[pattern]!
-    return r
 }
 
 let (towels, patterns) = try readInput(CommandLine.arguments[1])
-print(patterns.reduce(0) { s, p in s + matches(p, towels) })
+print(patterns.map{ matches($0, towels) }.reduce(0, +))