15a

Sources/15/15.swift

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+//
+//  File.swift
+//
+//
+//  Created by Max Nuding on 15s.12.21.
+//
+
+import Foundation
+import Runner
+import Collections
+
+typealias ThreatLevel = Int
+
+struct Coord: Hashable, CustomStringConvertible {
+    let row: Int
+    let col: Int
+    
+    var description: String { "(\(row), \(col))" }
+    
+    func neighbors() -> [Coord] {
+        [
+            Coord(row: row-1, col: col),
+            Coord(row: row, col: col+1),
+            Coord(row: row+1, col: col),
+            Coord(row: row, col: col-1)
+        ]
+    }
+}
+
+class Day15: Runnable {
+    let inputPath: String
+    var field = [Coord]()
+    var lastRow: Int = 0
+    var lastCol: Int = 0
+    var parts = [[ThreatLevel]]()
+    var neighbors = [Coord: [Coord]]()
+    
+    required init(inputPath: String) {
+        self.inputPath = inputPath
+    }
+    
+    public func run() {
+        let input = try! String(contentsOfFile: inputPath)
+        parts = input
+            .trimmingCharacters(in: .newlines)
+            .components(separatedBy: .newlines)
+            .map { Array($0) }
+            .map { ar in ar.map {c in ThreatLevel(c.description)!} }
+        lastRow = parts.count - 1
+        lastCol = (parts.first?.count ?? 0) - 1
+        
+        
+        var unvisited = Set<Coord>()
+        // Distances to startNode
+        var totalThreatLevel = [Coord: ThreatLevel]()
+        for row in parts.enumerated() {
+            for col in row.element.indices {
+                let c = Coord(row: row.offset, col: col)
+                unvisited.insert(c)
+                //totalThreatLevel[c] = Int.max
+            }
+        }
+        let startNode = Coord(row: 0, col: 0)
+        totalThreatLevel[startNode] = 0
+        
+        while let currentNode = unvisited.min(by: { totalThreatLevel[$0, default: Int.max] < totalThreatLevel[$1, default: Int.max] }) {
+            //var currentNode = !
+            unvisited.remove(currentNode)
+            if neighbors[currentNode] == nil {
+                neighbors[currentNode] = currentNode
+                    .neighbors()
+                    .filter {
+                        $0.col >= 0 && $0.col <= lastCol && $0.row >= 0 && $0.row <= lastRow
+                    }
+            }
+            var adjacent = neighbors[currentNode]!
+            neighbors[currentNode] = adjacent
+            adjacent = adjacent
+                .filter {
+                    unvisited.contains($0)
+                }
+            let currentThreatLevel = totalThreatLevel[currentNode, default: Int.max]
+            for a in adjacent {
+                let testCost = parts[a] + currentThreatLevel
+                if totalThreatLevel[a, default: Int.max] > testCost {
+                    totalThreatLevel[a] = testCost
+                }
+            }
+        }
+        print(totalThreatLevel[Coord(row: lastRow, col: lastCol)]!)
+    }
+}
+
+extension Array where Element == Array<Int> {
+    subscript(coord: Coord) -> Int {
+        get { self[coord.row][coord.col] }
+        set(newValue) {
+            self[coord.row][coord.col] = newValue
+        }
+    }
+}

Sources/15/main.swift

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+//
+//  File.swift
+//  
+//
+//  Created by Max Nuding on 15.12.21.
+//
+
+import Foundation
+import Runner
+
+//Runner(target: Day15.self, day: "15", isTest: true).run()
+Runner(target: Day15.self, day: "15", isTest: false).run()