both parts

Sources/15/15.swift

@@ -38,22 +38,11 @@ class Day15: Runnable {
         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
-        
+    private func expandMap() {
         var tmpParts = parts
         for (rowNum, row) in tmpParts.enumerated() {
             let newRow = [Int](0...4).flatMap { cr in
-                row
-                    .map { rv in cr + rv }
-                    .map { $0 > 9 ? $0 - 9 : $0 }
+                row.map { rv in cr + rv }.map { $0 > 9 ? $0 - 9 : $0 }
             }
             parts[rowNum] = newRow
         }
@@ -69,7 +58,25 @@ class Day15: Runnable {
         
         lastRow = parts.count - 1
         lastCol = (parts.first?.count ?? 0) - 1
+    }
     
+    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
+        
+        calculateSafestPath()
+        expandMap()
+        neighbors = [Coord: [Coord]]()
+        calculateSafestPath()
+    }
+    
+    private func calculateSafestPath() {
         // Distances to startNode
         var totalThreatLevel = [Coord: ThreatLevel]()
         
@@ -78,6 +85,13 @@ class Day15: Runnable {
                 Coord(row: row.offset, col: col)
             }
         })
+        
+        /* Keep a seperate dictionary, to calculate which coordinates have a set threat level
+         * a.k.a total distance to start
+         * This allows to find the next coordinate to check fairly quickly, by just
+         * looking at the minmum key in this.
+         * I initially tried a PriorityQueue, but my implementation was pretty slow and it spent too much time sorting
+         */
         var threatLevelDistrubution = [ThreatLevel: Set<Coord>]()
         let startNode = Coord(row: 0, col: 0)
         totalThreatLevel[startNode] = 0
@@ -89,6 +103,8 @@ class Day15: Runnable {
             let currentNode = threatLevelDistrubution[threatLevel]!.first!
             unvisited.remove(currentNode)
             threatLevelDistrubution[threatLevel]!.remove(currentNode)
+            
+            // Remove key from dictionary if not coords are left for a specific threat level
             if threatLevelDistrubution[threatLevel]!.isEmpty {
                 threatLevelDistrubution.removeValue(forKey: threatLevel)
             }
@@ -114,6 +130,8 @@ class Day15: Runnable {
                     totalThreatLevel[a] = testCost
                     threatLevelDistrubution[currentCost]!.remove(a)
                     threatLevelDistrubution[testCost, default: Set<Coord>()].insert(a)
+                    
+                    // Remove key from dictionary if not coords are left for a specific threat leveli
                     if threatLevelDistrubution[currentCost]!.isEmpty {
                         threatLevelDistrubution.removeValue(forKey: currentCost)
                     }