Thread: Problem using DFS with a DAG graph

Hey there!
I'm using DFS to search how many paths do I have from vertex1 to vertex2 in a DAG graph... But I have a problem that I search the vertexes a "infinity" of times... I went here and I didn't quite understood the language or the ideas... Like "If vertex w is unexplained then"...

So here's my code

Code:

typedef struct node { 
	int v;
	struct node *next;
} Node;

typedef Node *ADJ;

int n_paths(int vertex1, int vertex2) {
	int n = 0;
	ADJ temp;
	temp = graph[vertex1];
	if(vertex1 == vertex2)
		return 1;
	while(temp != NULL) {
		n = n + n_paths(temp->v, vertex2);
		temp = temp->next;
	}
	return n;
}

I ommited a big part of the code because I think this is the most important part... Any ideas how to optimize?
Thnx!

i don't because a DAG is an acyclic graph...