14a (bad version)

Sources/14/14.swift

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+//
+//  File.swift
+//
+//
+//  Created by Max Nuding on 14.12.21.
+//
+
+import Foundation
+import Runner
+
+struct Replacement {
+    let from: String
+    let to: String
+    
+    init(line: String) {
+        let r = line.components(separatedBy: " -> ")
+        from = r.first!
+        to = r.last!
+    }
+    
+    func replace(pair: String) -> String.Element? { pair == from ? to.first : nil }
+}
+
+class Day14: Runnable {
+    let inputPath: String
+    
+    required init(inputPath: String) {
+        self.inputPath = inputPath
+    }
+    
+    public func run() {
+        let input = try! String(contentsOfFile: inputPath)
+        let parts = input
+            .trimmingCharacters(in: .newlines)
+            .components(separatedBy: "\n\n")
+        var startingPolymer = parts.first!
+        let replacements = parts.last!
+            .components(separatedBy: .newlines)
+            .map(Replacement.init)
+        
+        for step in 1...10 {
+            var inserts = [(String.Index, Character)]()
+            for i in startingPolymer.indices {
+                let next = startingPolymer.index(i, offsetBy: 1)
+                guard next != startingPolymer.endIndex else {
+                    continue
+                }
+                var pair = startingPolymer[i]/* + startingPolymer[next]*/
+                let p = "\(startingPolymer[i])\(startingPolymer[next])"
+                for replacement in replacements {
+                    if let c = replacement.replace(pair: p) {
+                        inserts.append((next, c))
+                        break
+                    }
+                }
+            }
+            
+            var tmp = startingPolymer
+            var count = 0
+            for r in inserts {
+                let idx = tmp.index(r.0, offsetBy: count)
+                tmp.insert(r.1, at: idx)
+                count += 1
+            }
+            startingPolymer = tmp
+        }
+        let charCounts = startingPolymer.reduce(into: [String.Element: Int](), {
+            $0[$1, default: 0] += 1
+        })
+        let maxC = charCounts.max(by: {$0.value < $1.value })!
+        let minC = charCounts.min(by: {$0.value < $1.value })!
+        print(maxC.value - minC.value)
+    }
+}

Sources/14/main.swift

@@ -0,0 +1,12 @@
+//
+//  File.swift
+//  
+//
+//  Created by Max Nuding on 14.12.21.
+//
+
+import Foundation
+import Runner
+
+//Runner(target: Day14.self, day: "14", isTest: true).run()
+Runner(target: Day14.self, day: "14", isTest: false).run()