Added parser for DIMACS format + some examples.

1 files changed, 45 insertions, 0 deletions

diff --git a/graph.c b/graph.c
index e6be1c1..a957136 100644
--- a/graph.c
+++ b/graph.c
@@ -29,6 +29,51 @@ graph load_graph(FILE *stream) {
 	return k;
 }
 
+graph load_graph_dimacs(FILE *stream) {
+	int i, n, m, a, b;
+
+	
+	char buf = fgetc(stream);
+	while (buf == 'c') {
+		buf = fgetc(stream);
+		if (buf == '\n') buf = fgetc(stream);
+		else buf = 'c';
+	}
+	if (buf != 'p') {
+		fprintf(stderr, "File format error (expected 'p' declaration)\n");
+		return NULL;
+	}
+	fscanf(stream, " col %d %d\n", &n, &m);	// read node count
+	fprintf(stderr, "Load DIMACS: n = %d, m = %d\n", n, m);
+
+	graph k = malloc(sizeof(struct graph_descriptor));
+	k->N = n;
+	k->neighbour = malloc(n * sizeof(set));
+	for (i = 0; i < n; i++) k->neighbour[i] = empty_set(n);
+	
+	for (i = 0; i < m; i++) {
+
+		buf = fgetc(stream);
+		while (buf == 'c') {
+			buf = fgetc(stream);
+			if (buf == '\n') buf = fgetc(stream);
+			else buf = 'c';
+		}
+		if (buf != 'e') {
+			fprintf(stderr, "File format error (expected 'e' declaration)\n");
+			return NULL;
+		}
+
+		fscanf(stream, " %d %d\n", &a, &b);
+		fprintf(stderr, "Edge: (%d, %d)\n", a, b);
+		a--; b--;
+		set_add_ip(b, k->neighbour[a]);
+		set_add_ip(a, k->neighbour[b]);
+	}
+
+	return k;
+}
+
 const set graph_neighbours(const graph g, int n) {
 	return g->neighbour[n];
 }