09a

Sources/09/09.swift

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+//
+//  File.swift
+//
+//
+//  Created by Max Nuding on 05.12.21.
+//
+
+import Foundation
+import Runner
+import Collections
+
+struct Coord {
+    let row: Int
+    let col: Int
+    
+    func getLeft() -> Coord? {
+        guard col > 0 else {
+            return nil
+        }
+        return Coord(row: row, col: col - 1)
+    }
+    
+    func getRight() -> Coord { Coord(row: row, col: col + 1) }
+    
+    func getAbove() -> Coord? {
+        guard row > 0 else {
+            return nil
+        }
+        return Coord(row: row - 1, col: col)
+    }
+    
+    func getBelow() -> Coord { Coord(row: row + 1, col: col) }
+}
+
+struct Field {
+    let numbers: [[Int]]
+    let numCols: Int
+    let numRows: Int
+    
+    init(numbers: [[Int]]) {
+        self.numbers = numbers
+        numCols = numbers.first!.count
+        numRows = numbers.count
+    }
+    
+    func getNeighborsCoordsFor(coord: Coord) -> [Coord] {
+        return [coord.getAbove(), coord.getRight(), coord.getBelow(), coord.getLeft()]
+            .compactMap { $0 }
+            .filter { $0.row < numRows && $0.col < numCols }
+    }
+    
+    func lowPointValueAt(coord: Coord) -> Int? {
+        let value = numbers[coord.row][coord.col]
+        return getNeighborsCoordsFor(coord: coord)
+            .map { numbers[$0.row][$0.col] }
+            .allSatisfy { $0 > value }
+        ? value
+        : nil
+    }
+}
+
+struct Day09: Runnable {
+    let inputPath: String
+    
+    func run() {
+        let input = try! String(contentsOfFile: inputPath)
+        let entries = input
+            .trimmingCharacters(in: .newlines)
+            .components(separatedBy: .newlines)
+            .map { line in line.map { $0.wholeNumberValue! } }
+        let field = Field(numbers: entries)
+        var sum = 0
+        for row in 0..<field.numRows {
+            for col in 0..<field.numCols {
+                if let lpv = field.lowPointValueAt(coord: Coord(row: row, col: col)) {
+                    sum += lpv + 1
+                }
+            }
+        }
+        print(sum)
+    }
+}

Sources/09/main.swift

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+//
+//  File.swift
+//  
+//
+//  Created by Max Nuding on 05.12.21.
+//
+
+import Foundation
+import Runner
+
+//Runner(target: Day09.self, day: "09", isTest: true).run()
+Runner(target: Day09.self, day: "09", isTest: false).run()