POJ 3259 Wormholes

POJ 3259 Wormholes

SPFA判负权回路。
以下是我的代码：

#include < queue >
#include < cstdio >
#include < cstring >
using   namespace  std;
const   int  kMaxn( 507 );
const   int  kMaxm( 5207 );
const   long   long  kInf(0x7f7f7f7f7f7f7f7fll);

struct  Edge
{
     int  v,w;
};

int  n,m,w;
int  cnt,first[kMaxn],next[kMaxm];Edge e[kMaxm];

void  AddEdge( int  u, int  v, int  w)
{
    cnt ++ ;
    e[cnt].v = v;e[cnt].w = w;
    next[cnt] = first[u];
    first[u] = cnt;
}

bool  SPFA()
{
     long   long  dist[kMaxn];
    queue < int >  q;
     int  num[kMaxn] = { 0 };
     bool  inq[kMaxn] = { false };
     for ( int  i = 1 ;i <= n;i ++ )
        dist[i] = (i == 1 ? 0 :kInf);
    q.push( 1 );
    inq[ 1 ] = true ;
    num[ 1 ] ++ ;
     while ( ! q.empty())
    {
         int  u(q.front());q.pop();
        inq[u] = false ;
         if (num[u] > n)
             return   true ;
         for ( int  i = first[u];i !=- 1 ;i = next[i])
        {
             int  v(e[i].v),w(e[i].w);
             if (dist[v] > dist[u] + w)
            {
                dist[v] = dist[u] + w;
                 if ( ! inq[v])
                {
                    q.push(v);
                    inq[v] = true ;
                    num[v] ++ ;
                }
            }
        }
    }
     return   false ;
}

int  main()
{
     int  T;
    scanf( " %d " , & T);
     while (T -- )
    {
        scanf( " %d%d%d " , & n, & m, & w);
        cnt = 0 ;
        memset(first, - 1 , sizeof (first));
         for ( int  i = 1 ;i <= m;i ++ )
        {
             int  u,v,w;
            scanf( " %d%d%d " , & u, & v, & w);
            AddEdge(u,v,w);
            AddEdge(v,u,w);
        }
         for ( int  i = 1 ;i <= w;i ++ )
        {
             int  u,v,w;
            scanf( " %d%d%d " , & u, & v, & w);
            AddEdge(u,v, - w);
        }

         if (SPFA())
            printf( " YES\n " );
         else
            printf( " NO\n " );
    }

     return   0 ;
}