POJ 1523 SPF

POJ 1523 SPF

求无向连通图的割点，使用Tarjan算法。
以下是我的代码：

#include < algorithm >
#include < cstdio >
#include < cstring >
using   namespace  std;
const   int  kMaxn( 1007 );

int  n,m;
bool  g[kMaxn][kMaxn];

int  root,root_son,cnt,dfsn[kMaxn],low[kMaxn],subnet[kMaxn];
bool  used[kMaxn];

void  dfs( int  u)
{
    cnt ++ ;
    dfsn[u] = low[u] = cnt;
    used[u] = true ;

     for ( int  v = 1 ;v <= n;v ++ )
    {
         if (g[u][v])
        {
             if ( ! used[v])
            {
                dfs(v);
                low[u] = min(low[u],low[v]);
                 if (low[v] >= dfsn[u])
                {
                     if (u != root)
                        subnet[u] ++ ;
                     else
                        root_son ++ ;
                }
            }
             else
                low[u] = min(low[u],dfsn[v]);
        }
    }
}

void  Tarjan()
{
    root = n;

    cnt = 1 ;
    root_son = 0 ;
    memset(used, false ,kMaxn * sizeof ( bool ));
     for ( int  i = 1 ;i <= n;i ++ )
        subnet[i] = 1 ;

    dfs(root);

     if (root_son > 1 )
        subnet[root] = root_son;
}

int  main()
{

     int  T( 0 ),u,v;
     while ( true )
    {
        n = 0 ;
        memset(g, false ,kMaxn * kMaxn * sizeof ( bool ));
         bool  test( false );
         while (scanf( " %d " , & u) == 1 )
        {
             if (u)
            {
                test = true ;
                scanf( " %d " , & v);
                g[u][v] = g[v][u] = true ;
                n = max(n,max(u,v));
            }
             else
                 break ;
        }

         if ( ! test)
             break ;

        T ++ ;
         if (T != 1 )
            printf( " \n " );
        printf( " Network #%d\n " ,T);

        Tarjan();

         bool  found( false );
         for ( int  i = 1 ;i <= n;i ++ )
             if (subnet[i] > 1 )
            {
                found = true ;
                printf( "   SPF node %d leaves %d subnets\n " ,i,subnet[i]);
            }
         if ( ! found)
            printf( "   No SPF nodes\n " );
    }

     return   0 ;
}