int no_path(int a[], int n, int start)
{
static int count =0;
if(start == n-1)
{
count++;
return count;
}
if(start+1<n)
no_path(a,n,start+1);
if(start+2<n)
no_path(a,n,start+2);
return count;
}
struct path *find_shortest_ (int **weights, struct path **cache, struct node **graph, int id1, int id2) {
printf ("id1: %d, id2: %d\n", id1, id2);
if (id1 == id2) {
struct path *stub = new_path (id1);
cache[id1] = stub;
return stub;
}
// If the path passed to us is a cycl
//struct node *start = get_node (graph, id1);
struct node *end = get_node (graph, id2);
// Get all of the shortest paths for the predecessors
// Also, the shortest path to us is us plus the shortest of the paths to our
// predecessors
int i;
int min = 65535;
int minpath = 0;
for (i = 0; i < end->num_back; i++) {
struct path *cur = cache[end->back[i]];
// Only do work if we have to
if (cur == NULL) {
cur = find_shortest_ (weights, cache, graph, id1, end->back[i]);
}
// Now we definitely have a value
if (cur->numelems > 0 && cur->length + weights[end->back[i]][id2] < min) {
min = cur->length + weights[end->back[i]][id2];
minpath = end->back[i];
}
}
// If there's no path, return that
// We also get here if there's nobody behind us
if (min == 65535)
return no_path ();
// Add us to the cache and return
struct path *our_shortest = add_stop (weights, cache[minpath], minpath, id2);
// If we've cycled (only happens if there's a negative cycle) then print out
// that we have a negative cycle and the path that has it
// Might not terminate if we do... Hmm...
if (has_cycle (our_shortest)) {
printf ("======== We have a cycle =======\n");
print_path (our_shortest);
printf("================\n");
}
// Add us to the cache
cache[id2] = our_shortest;
return our_shortest;
}
