ok1(agar_dijkstra_path(sr, int2ptr(3), &cost, NULL, NULL));
ok1(cost == 0);
ok1(!agar_dijkstra_path(sr, int2ptr(4), &cost, NULL, NULL));
ok1(agar_dijkstra_path(sr, int2ptr(3), &cost, NULL, NULL));
ok1(cost == 0);
ok1(!agar_dijkstra_path(sr, int2ptr(4), &cost, NULL, NULL));