Zoj 1119

#include <iostream>
#include <cstring>

using namespace std;
#define min(a, b) (a < b ? a : b)

int Edge[1001][1001];
int visited[1001];
int low[1001];
int dfn[1001];
int nodes;
int tmpdfn;
int subnets[1001];
int sons;
void DFS( int u )
{
for(int v = 1; v <= nodes; ++v)
{
if(Edge[u][v])
{
if(!visited[v])
{
visited[v] = 1;
tmpdfn++;
low[v] = dfn[v] = tmpdfn;
DFS( v );
low[u] = min(low[u], low[v]);
if(low[v] >= dfn[u])
{
if(u != 1)
subnets[u]++;
if(u == 1)
sons++;
}
}
else
low[u] = min(low[u], dfn[v]);
}
}
}

void inite()
{
sons = 0;
tmpdfn = 1;
low[1] = dfn[1] = 1;
memset( visited, 0, sizeof(visited));
visited[1] = 1;
memset( subnets, 0, sizeof(subnets));
}

int main()
{
int i;
int u, v;
int kfind;
int number = 1;
while( 1 )
{
cin>>u;
if(u == 0)
break;
memset(Edge, 0, sizeof(Edge));
nodes = 0;
cin>>v;
if(nodes < u)
nodes = u;
if(nodes < v)
nodes = v;
Edge[u][v] = Edge[v][u] = 1;
while(1)
{
cin>>u;
if(u == 0)
break;
cin>>v;
if(u > nodes)
nodes = u;
if(v > nodes)
nodes = v;
Edge[u][v] = Edge[v][u] = 1;
}
if(number > 1)
cout<<endl;
cout<<"Network #"<<number<<endl;
number++;
inite();
DFS( 1 );
if(sons > 1)
subnets[1] = sons - 1;
kfind = 0;
for(i = 1; i <= nodes; ++i)
{
if(subnets[i])
{
kfind = 1;
cout<<"  SPF node "<<i<<" leaves "<<subnets[i] + 1<<" subnets"<<endl;
}
}
if( !kfind )
{
cout<<"  No SPF nodes"<<endl;
}

}
return 0;
}