POJ 2240 Arbitrage

POJ 2240 Arbitrage

用BellmanFord求最长路。
以下是我的代码：

#include < iostream >
#include < string >
#include < map >
#include < algorithm >
#include < cstdio >
using   namespace  std;
const   int  kMaxn( 37 );
struct  Edge
{
     int  u,v;
     double  w;
};

int  n,m;
Edge e[kMaxn * kMaxn];

bool  BellmanFord( int  s)
{
     double  d[kMaxn];
     for ( int  i = 1 ;i <= n;i ++ )
        d[i] = (i == s ? 1 : 0 );
     for ( int  i = 1 ;i <= n;i ++ )
         for ( int  j = 1 ;j <= m;j ++ )
        {
             int  u(e[j].u),v(e[j].v);
             double  w(e[j].w);
            d[v] = max(d[v],d[u] * w);
        }
     return  d[s] > 1 ;
}

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

     int  T( 0 );
     while (cin >> n  &&  n)
    {
        map < string , int >  id;
         for ( int  i = 1 ;i <= n;i ++ )
        {
             string  t;
            cin >> t;
            id[t] = i;
        }
        cin >> m;
         for ( int  i = 1 ;i <= m;i ++ )
        {
             string  t1,t2;
            cin >> t1 >> e[i].w >> t2;
            e[i].u = id[t1];
            e[i].v = id[t2];
        }

         bool  success( false );
         for ( int  i = 1 ;i <= n;i ++ )
             if (BellmanFord(i))
            {
                success = true ;
                 break ;
            }

        printf( " Case %d:  " , ++ T);
         if (success)
            printf( " Yes\n " );
         else
            printf( " No\n " );
    }

     return   0 ;
}