15b slow version, do not use

Sources/15/15.swift

@@ -49,6 +49,27 @@ class Day15: Runnable {
         lastRow = parts.count - 1
         lastCol = (parts.first?.count ?? 0) - 1
         
+        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 }
+            }
+            parts[rowNum] = newRow
+        }
+        
+        tmpParts = parts
+        for num in 1...4 {
+            for i in tmpParts.indices {
+                let tr = tmpParts[i]
+                let ntr = tr.map { $0 + num }.map { $0 > 9 ? $0 - 9 : $0 }
+                parts.append(ntr)
+            }
+        }
+        
+        lastRow = parts.count - 1
+        lastCol = (parts.first?.count ?? 0) - 1
         
         var unvisited = Set<Coord>()
         // Distances to startNode