int top = -1;

int  stack[MAX_NODES][2];

void add(int,int);

void delete(int *,int *);

void add(int x, int y)

{

   stack[++top][0] = x;

   stack[top][1] = y;

}

void delete(int *x, int *y)

{

   *x = stack[top][0];

   *y = stack[top--][1];

}

void bicon(int u, int v)

{

/* compute dfn and low, and output the edges of G by their

biconnected components, v is the parent (if any) of the spanning

tree of u.  dfn[0] to dfn[MAX_SIZE] is initialized to -1, and

num is set to 0 before the function begins */

   NodePointer ptr;

   int w,x,y;

   dfn[u] = low[u] = num++;

   for (ptr = graph[u]; ptr; ptr = ptr->link)  {

      w = ptr->vertex;

      if (v != w && dfn[w] < dfn[u])

	       add(u,w);

      if (dfn[w] <0) { /* w has not been visited */

	bicon(w,u);

	low[u] = MIN2(low[u],low[w]);

	if (low[w] >= dfn[u]) {

	  printf("New biconnected component: ");

	  do {

	     delete(&x,&y);

	     printf("\t<%2d,%2d>",x,y);

	   } while (!((x == u) && (y == w)));

	   printf("\n");

	 }

      }

      else if (w != v)

	low[u] = MIN2(low[u],dfn[w]);

   }

}