06b

Sources/06/06.swift

@@ -8,25 +8,6 @@
 import Foundation
 import Runner
 
-class Fish: CustomStringConvertible {
-    var timer: Int
-    
-    var description: String { "\(timer)"}
-    
-    init(timer: Int = 8) {
-        self.timer = timer
-    }
-    
-    func tick() -> Fish? {
-        timer -= 1
-        if timer < 0 {
-            timer = 6
-            return Fish()
-        }
-        return nil
-    }
-}
-
 struct Day06: Runnable {
     let inputPath: String
     
@@ -35,15 +16,26 @@ struct Day06: Runnable {
         let internalCounters = input
             .trimmingCharacters(in: .newlines)
             .components(separatedBy: ",")
-            .map { Fish(timer: Int($0)!) }
+            .map { Int($0)! }
         run(fish: internalCounters, numDays: 80)
+        run(fish: internalCounters, numDays: 256)
     }
     
-    func run(fish: [Fish], numDays: Int) {
-        var tmpFish = fish
-        for _  in 1...numDays {
-            tmpFish.append(contentsOf: tmpFish.compactMap { $0.tick() })
+    func run(fish: [Int], numDays: Int) {
+        var tmpFish = Dictionary(grouping: fish, by: { $0 }).mapValues { $0.count }
+        
+        for _ in 1...numDays {
+            var d = [Int:Int]()
+            for f in tmpFish.keys.filter({$0 >= 0}) {
+                d[f-1] = tmpFish[f]
+            }
+            let countPregnant = d[-1] ?? 0
+            d[8] = countPregnant
+            d[6] = (d[6] ?? 0) + countPregnant
+            d[-1] = 0
+            
+            tmpFish = d
         }
-        print(tmpFish.count)
+        print(tmpFish.values.reduce(0, +))
     }
 }

Sources/Runner/Resources/input/06_test.txt

@@ -0,0 +1 @@
+3,4,3,1,2