2022_12: golang solution(part 2)

2022/day_12/golang/graph/bfs.go

@@ -29,6 +29,39 @@ func GetShortestPath(startVertex *Vertex, endCoords Coords) int {
 			}
 
 			key = neighbour.Key()
+			if !visited[key] {
+				queue = append(queue, BFSNode{vertex: neighbour, distance: node.distance + 1})
+				visited[key] = true
+			}
+		}
+	}
+
+	return -1
+}
+
+func FindShortestPathToValue(startVertex *Vertex, targetValue byte) int {
+	visited := make(map[Coords]bool)
+	queue := make([]BFSNode, 0)
+
+	queue = append(queue, BFSNode{vertex: startVertex, distance: 0})
+	visited[startVertex.Key()] = true
+
+	for len(queue) > 0 {
+		node := queue[0]
+		queue = queue[1:]
+
+		if node.vertex.value == targetValue {
+			return node.distance
+		}
+
+		nextNeighbour := node.vertex.Iter()
+		for {
+			neighbour := nextNeighbour()
+			if neighbour == nil {
+				break
+			}
+
+			key := neighbour.Key()
 
 			if !visited[key] {
 				queue = append(queue, BFSNode{vertex: neighbour, distance: node.distance + 1})

2022/day_12/golang/main.go

@@ -21,7 +21,12 @@ func main() {
 		panic("startVertex is nil")
 	}
 
-	shortestPath := graph.GetShortestPath(startVertex, endCoords)
+	endVertex := g.GetVertex(endCoords)
+	if endVertex == nil {
+		panic("endVertex is nil")
+	}
+
+	shortestPath := graph.FindShortestPathToValue(endVertex, byte('a')-96)
 
 	fmt.Println(shortestPath)
 }
@@ -92,7 +97,11 @@ func ConnectVertexesByTarget(v1 *graph.Vertex, v2 *graph.Vertex) {
 		return
 	}
 
-	if int(v2.Value())-int(v1.Value()) <= 1 {
+	delta := int(v2.Value()) - int(v1.Value())
+
+	// for part one with going up -> (v <= 1)
+	// for part two with going down -> (v >= -1)
+	if delta >= -1 {
 		v1.AddEdge(v2)
 	}
 }