POJ 1789 Truck History

POJ 1789 Truck History

MST问题。
以下是我的代码：

#include < iostream >
#include < string >
#include < cstdio >
using   namespace  std;
const   int  kMaxn( 2007 );
const   int  kInf( 0x7f7f7f7f );

int  n,g[kMaxn][kMaxn];
string  name[kMaxn];
int  mst,lowcost[kMaxn];

int  dist( int  a, int  b)
{
     int  re( 0 );
     for ( int  i = 0 ;i < 7 ;i ++ )
         if (name[a][i] != name[b][i])
            re ++ ;
     return  re;
}

void  Prim()
{
    mst = 0 ;
     for ( int  i = 1 ;i <= n;i ++ )
        lowcost[i] = g[ 1 ][i];
    lowcost[ 1 ] =- 1 ;
     for ( int  i = 1 ;i <= n - 1 ;i ++ )
    {
         int  v( - 1 ),w(kInf);
         for ( int  j = 1 ;j <= n;j ++ )
             if (lowcost[j] !=- 1   &&  w > lowcost[j])
            {
                v = j;
                w = lowcost[j];
            }
         if (v !=- 1 )
        {
            mst += w;
            lowcost[v] =- 1 ;
             for ( int  j = 1 ;j <= n;j ++ )
                 if (lowcost[j] !=- 1   &&  lowcost[j] > g[v][j])
                    lowcost[j] = g[v][j];
        }
    }
}

int  main()
{
     /*
    freopen("data.in","r",stdin);
    freopen("data.out","w",stdout);
    // */

     while (cin >> n  &&  n)
    {
         for ( int  i = 1 ;i <= n;i ++ )
            cin >> name[i];
         for ( int  i = 2 ;i <= n;i ++ )
             for ( int  j = 1 ;j <= i - 1 ;j ++ )
                g[i][j] = g[j][i] = dist(i,j);

        Prim();

        printf( " The highest possible quality is 1/%d.\n " ,mst);
    }

     return   0 ;
}