void DFSShowGraphVertex(ALGraphDFS*graph,int startV){
Stack stack;
int visitV=startV;
int nextV;
StackInit(&stack);
VisitVertex(graph,visitV);
SAPush(&stack,visitV);
while(LDFirst(&(graph->list[visitV]),&nextV)==TRUE){
int visitFlag=FALSE;
if(VisitVertex(graph,nextV)==TRUE){
SAPush(&stack,visitV);
visitV=nextV;
visitFlag=TRUE;
}
else{
while(LDNext(&(graph->list[visitV]),&nextV)==TRUE){
if(VisitVertex(graph,nextV)==TRUE){
SAPush(&stack,visitV);
visitV=nextV;
visitFlag=TRUE;
break;
}
}
}
if(visitFlag==FALSE){
if(SABIsEmpty(&stack)==TRUE) break;
else visitV=SABPop(&stack);
}
}
memset(graph->visit,0,sizeof(int)*graph->numV);
}
void BFSShowGraphVertex(ALGraphBFS *graph,int startV){
Queue queue;
int visitV=startV;
int nextV;
CQueueInit(&queue);
VisitVertex(graph,visitV);
while(LDFirst(&(graph->list[visitV]),&nextV)==TRUE){
if(VisitVertex(graph,nextV)==TRUE)
CEnqueue(&queue,nextV);
while(LDNext(&(graph->list[visitV]),&nextV)==TRUE){
if(VisitVertex(graph,nextV)==TRUE) CEnqueue(&queue,nextV);
}
if(CQIsEmpty(&queue)==TRUE) break;
else visitV=CDequeue(&queue);
}
memset(graph->visit,0,sizeof(int)*graph->numV);
}
void VisitVertex(struct Graph *G, int *par, int *comp, int v)
{
int i, component = 1;
for (comp[v] = component, i = 0; i < G[v].size; i++)
{
if (comp[G[v].arr[i]] == -1 && par[G[v].arr[i]] != v)
{
VisitVertex(G, par, comp, G[v].arr[i]);
}
}
}
int main()
{
struct Queue q;// = malloc(14000000000 * sizeof(int));
int v;
int i;
int n, m;
scanf("%d", &n);
scanf("%d", &m);
char *last = calloc(n, sizeof(char));
int *par = calloc(n, sizeof(int));
int *component = calloc(n, sizeof(int));
struct Graph *G = malloc(n * sizeof(struct Graph));
for (i = 0; i < n;)
{
G[i].size = last[i] = 0;
component[i++] = -1;
}
for (i = m; i > 0; i--)
{
int a, b;
scanf("%d %d", &a, &b);
G[a].arr[G[a].size++] = b;
G[b].arr[G[b].size++] = a;
}
int comp = 1;
for (q.head = q.tail = i = 0; i < n; q.head = q.tail = 0, i++)
{
if (!last[i])
{
comp--;
DFSRec(G, &q, par, i, last);
}
for (v = -1; QueueEmpty(&q);)
{
v = q.mas[q.head++];
if (component[v] == -1)
{
VisitVertex(G, par, component, v);
comp++;
}
}
}
printf("%d\n", comp - 1);
//free(q);
free(G);
free(last);
free(par);
free(component);
return 0;
}
