day23: started hardcode of part2, way too slow

day23/field.go

@@ -27,6 +27,35 @@ type Field struct {
 	StartCol, EndCol int
 }
 
+func (f *Field) NeighborsPart2(c Coord) (neighbors []Coord) {
+	symb, exists := f.Cells[c]
+	if !exists {
+		panic(fmt.Sprintf("coord %+v not found in field", c))
+	}
+
+	var coords []Coord
+	switch symb {
+	case Tree:
+		panic(fmt.Sprintf("attempting to get neighbors of a tree at %+v", c))
+	default:
+		coords = []Coord{
+			{Row: c.Row + 1, Col: c.Col},
+			{Row: c.Row - 1, Col: c.Col},
+			{Row: c.Row, Col: c.Col + 1},
+			{Row: c.Row, Col: c.Col - 1},
+		}
+	}
+
+	for _, coord := range coords {
+		neighborSymb, found := f.Cells[coord]
+		if !found || neighborSymb == Tree {
+			continue
+		}
+		neighbors = append(neighbors, coord)
+	}
+	return
+}
+
 func (f *Field) Neighbors(c Coord) (neighbors []Coord) {
 	symb, exists := f.Cells[c]
 	if !exists {