How can I improve running time in C - c

Question

I repeat this function 2500 times in a loop for different parameters and it takes 85 seconds. What is wrong with this function? How can I improve running time? Thanks for your help.
Function:
int findBaconNumber(v * actors[], int actorCount, int index, v * visited[]){
// Bacon number is 0:
if(strcmp(actors[index]->name, "Bacon,Kevin") == 0)
return 0;
// Bacon number is infinite:
else if(actors[index]->next == NULL)
return -1;
// Otherwise, calculate:
memset(visited, NULL, sizeof(visited));
q * queue = createQueue();
v * tmp = actors[index];
v * found;
n * tmp2;
int baconNumber = 0;
int visitCount = 0;
int empty = 0;
int full = 0;
// Add first item to queue:
enqueue(queue, tmp);
visited[visitCount] = tmp;
visitCount++;
tmp->parent = NULL;
// Until queue is empty, queue is full or kevin bacon found:
while(strcmp(tmp->name, "Bacon, Kevin") != 0 && isEmpty(queue) != 1 && isFull(queue) != 1){
// Get neighbors:
if(tmp->next != NULL)
tmp2 = tmp->next;
else
tmp2 = NULL;
// Add neighbors to queue:
while(tmp2 != NULL){
if(contains(visited,visitCount+1,actors[tmp2->actorNo]) != 1){
enqueue(queue, actors[tmp2->actorNo]);
visited[visitCount] = actors[tmp2->actorNo];
visitCount++;
actors[tmp2->actorNo]->parent = tmp;
}
tmp2 = tmp2->next;
}
// Dequeue current item and skip to next item:
dequeue(queue);
// Get next item in queue:
if(getFront(queue) != NULL)
tmp = getFront(queue);
}
if(strcmp(tmp->name, "Bacon, Kevin") != 0)
return -1;
while(tmp->parent != NULL && tmp != NULL){
baconNumber++;
tmp = tmp->parent;
}
return baconNumber;
}
For Loop:
for(i=0; i<actorCount; i++){
baconNumbers[i] = findBaconNumber(actors, actorCount, i, visited);
}
EDIT:
Thanks all of you for answers. This is my school project and it must be solved by breadth first search algorithm so I can not use other solutions. I profiled the code it looks like the problem is with the contains function. I use it to check if node is visited or not. Now, I am working on finding another solution for this.
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Answer 1

Some things that gets to messy to write in comments:
1) Use a profiler to find out what parts of the code that is actually taking time. It can be wise to break out all loops into functions to get more useful information from the profiler.
2) Use the information from the profiler to optimize the code
You're not showing the implementation of queue. That could be the bottleneck. If it is, there are basically two ways to attack it. Either try to optimize the queue code, or change the overall algorithm to use the queue less or in a smarter way.
Solving the Bacon number is basically a shortest path problem, so you might want to tinker with different algorithms. Dijkstras and A* are common shortest path algorithms.
Another thing you might look into is preprocessing the data. Right now, you have a struct array, and the structs have a field called name. Maybe you could change this to an int where 1 indicates that the name is "Bacon,Kevin" and 0 that it's not. That would save you potentially costly calls to strcmp and might also make it more cache friendly.
You might want to change the representation completely. Right now, I get the impression that you have something like this:
struct actor {
struct actor *parent, *next;
char *name;
}
I already mentioned that you could change name to a simple integer, but perhaps you could also change everything to:
int *names;
int *parents;
int *next;
That could make the code a lot more cache friendly. Or not. But it is worth trying. Linked lists are usually not very cache friendly. And this can be good to think about when it comes to the queue too.
Also, you might have a look at this: Calculating "Kevin Bacon" Numbers

Answer 2

I solved this problem with your helpful advices.
The way I used before (Too slow => takes 85 seconds for my input):
-When a node is visited, append this node to the end of visited[] array.
-Checking if node is visited or not by looping over all elements of visited[] array (via contains() function)
Faster way which I am using now (1.75 seconds for the same input):
-When a node is visited, assign this node to related index => (visited[actorNumber] = node;)
-Checking if node is visited or not without looping over all elements, only checking the related index.
I also removed strcmp and I am checking by index now.
Updated code is here:
int findBaconNumber(v * actors[], int actorCount, int index, int baconsIndex){
// Bacon number is 0:
if(actors[index]->index == baconsIndex)
return 0;
// Bacon number is infinite:
else if(actors[index]->next == NULL)
return -1;
// Otherwise, calculate:
q * queue = createQueue();
v * visited[ACTORS_SIZE] = {};
v * tmp = actors[index];
v * found;
n * tmp2;
int baconNumber = 0;
int empty = 0;
int full = 0;
// Add first item to queue:
enqueue(queue, tmp);
visited[tmp->index] = tmp;
tmp->parent = NULL;
// Until queue is empty, queue is full or kevin bacon found:
while(tmp->index != baconsIndex && isEmpty(queue) != 1 && isFull(queue) != 1){
// Get neighbors:
if(tmp->next != NULL)
tmp2 = tmp->next;
else
tmp2 = NULL;
// Add neighbors to queue:
while(tmp2 != NULL){
// If not visited:
if(visited[tmp2->actorNo] == NULL){
enqueue(queue, actors[tmp2->actorNo]);
visited[tmp2->actorNo] = actors[tmp2->actorNo];
actors[tmp2->actorNo]->parent = tmp;
}
tmp2 = tmp2->next;
}
// Dequeue current item and skip to next item:
dequeue(queue);
// Get next item in queue:
if(getFront(queue) != NULL)
tmp = getFront(queue);
}
if(tmp->index != baconsIndex)
return -1;
while(tmp->parent != NULL && tmp != NULL){
baconNumber++;
tmp = tmp->parent;
}
return baconNumber;
}