08

Sources/08/08.swift

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+//
+//  File.swift
+//
+//
+//  Created by Max Nuding on 05.12.21.
+//
+
+import Foundation
+import Runner
+import Collections
+
+struct Day08: Runnable {
+    let inputPath: String
+    
+    func run() {
+        let input = try! String(contentsOfFile: inputPath)
+        let entries = input
+            .trimmingCharacters(in: .newlines)
+            .components(separatedBy: .newlines)
+            .map { $0.components(separatedBy: " | ") }
+        let lines = entries.reduce(into: [String:String](), { $0[$1.first!] = $1[1] })
+        runA(lines: lines)
+        print(lines.map { runB(line: $0) }.reduce(0, +))
+    }
+    
+    func runA(lines: [String : String]) {
+        let outputSignals = lines.values
+            .flatMap { $0.components(separatedBy: .whitespaces) }
+        let uniqueOutputSignals = outputSignals
+            .filter { $0.count == 2 || $0.count == 3 || $0.count == 4 || $0.count == 7 }
+            .count
+        print(uniqueOutputSignals)
+    }
+    
+    func runB(line: Dictionary<String,String>.Element) -> Int {
+        let uniqueInputSignalDict = line.key
+            .components(separatedBy: .whitespaces)
+            .reduce(into: [Int:String](), {
+                switch $1.count {
+                case 2:
+                    $0[1] = $1
+                case 3:
+                    $0[7] = $1
+                case 4:
+                    $0[4] = $1
+                case 7:
+                    $0[8] = $1
+                default:
+                    break
+                }
+            })
+        let outputSignals = line.value.components(separatedBy: .whitespaces)
+        let len = Double(outputSignals.count - 1)
+        return outputSignals.enumerated()
+            .map { Int(pow(10.0, len - Double($0.offset))) * guessDigit(inputSignals: uniqueInputSignalDict, outputSignal: $0.element)! }
+            .reduce(0, +)
+        
+    }
+    
+    func guessDigit(inputSignals: [Int:String], outputSignal: String) -> Int? {
+        switch outputSignal.count {
+        case 2:
+            return 1
+        case 3:
+            return 7
+        case 4:
+            return 4
+        case 5:
+            if inputSignals[1]!.allSatisfy({ outputSignal.contains($0) }) {
+                return 3
+            }
+            let isTwo = inputSignals[8]!
+                .filter { !inputSignals[4]!.contains($0) }
+                .allSatisfy { outputSignal.contains($0) }
+            return isTwo ? 2 : 5
+        case 6:
+            if inputSignals[4]!.allSatisfy({ outputSignal.contains($0) }) {
+                return 9
+            }
+            let isZero = inputSignals[7]!.allSatisfy { outputSignal.contains($0) }
+            return isZero ? 0 : 6
+        case 7:
+            return 8
+        default:
+            print("Invalid output signal: \(outputSignal)")
+            return nil
+        }
+    }
+}

Sources/08/main.swift

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+//
+//  File.swift
+//  
+//
+//  Created by Max Nuding on 05.12.21.
+//
+
+import Foundation
+import Runner
+
+//Runner(target: Day08.self, day: "08", isTest: true).run()
+Runner(target: Day08.self, day: "08", isTest: false).run()