Set
*dijkstra(Graph *g, Label v, int Home, int n) {
// for the school vertex v, find all indices for homes and put all into
// a set
Heap *H;
Edge *Eu;
Set *S;
int i, usize;
Label u;
float R[n], delta;
// create a heap to store the distance for every vertices
// and an array to store dist values
H = createHeap();
for (i=0;i<n;i++) {
if (i==v) {
insert(H, i, 0);
R[i]=0;
continue;
}
insert(H, i, INFINITY);
R[i] = INFINITY;
}
// then loop through the heap
while (H->n) {
// extract the min in the heap
u = removeMin(H);
// if dist of u exceeds 1km, stop the loop
if (R[u]>1000) {
break;
}
Eu = graph_get_edge_array(g, u, &usize);
for (i=0;i<usize;i++) {
if (R[Eu[i].u]>R[u]+ *(float*)(Eu[i].data)) {
delta = R[u] + *(float*)(Eu[i].data) - R[Eu[i].u];
changeKey(H, Eu[i].u, delta);
R[Eu[i].u] = R[u]+ *(float*)(Eu[i].data);
}
}
}
// now add all home indices with in the range of 1km into the set
S = set_new();
for (i=0;i<Home;i++) {
if (R[i]<=1000) {
set_add(S, i);
}
}
return S;
}
void Dijkstra(Graph *g,int source,Universe *Uni,int (cmp)(int,int)) {
int *dist;
dist = (int*)malloc(sizeof(int)*(g->number_of_vertices));
assert(dist);
//set all vertices distance to INF
for(int i=0;i<g->number_of_vertices;i++) {
dist[i] = INF;
}
Heap *Q = createHeap();
//insert everything into heap
for(int i=0;i<g->number_of_vertices;i++) {
if(i==source) {
insert_in_heap(Q,i,0,cmp);
}
else {
insert_in_heap(Q,i,INF,cmp);
}
}
// update the distance of source
dist[source] = 0;
while(!isEmpty(Q)) {
HeapItem min = removeTop(Q,cmp);
// min can't be > 1000, if so we can stop
if(min.key > MAX_KM) {
break;
}
// prune any schools, only houses
if(min.dataIndex < g->num_houses) {
insert(Uni, source-g->num_houses, min.dataIndex);
}
int n_edges;
//get all edges from min.dataIndex
Edge *edges = graph_get_edge_array(g,min.dataIndex,&n_edges);
for(int i=0;i<n_edges;i++) {
//update all the edges distances if there is a minimum
if(dist[edges[i].u] > (dist[min.dataIndex] +edges[i].weight)) {
dist[edges[i].u] = dist[min.dataIndex]+edges[i].weight;
// update the heap
changeKey(Q,edges[i].u,dist[edges[i].u],cmp);
}
}
}
}
