Bellman Ford(warm up-2 1005)

 

 数据弱,代码有问题,等待修正

 

#include  < iostream >
using   namespace  std;

__int64 lmax = 0x7FFFFFFF ;
const   long  MAXN = 1200 ;

__int64 hash[MAXN][MAXN];
__int64 Dis[MAXN];

long  Start,End;
long  m,n; // 点,边

int  main()
{
    lmax = lmax << 10 ;
     long  T;
    scanf( " %ld " , & T);

     while  (T -- )
    {
        scanf( " %ld " , & m);
        scanf( " %ld %ld " , & Start, & End);
        scanf( " %ld " , & n);
         long  i,ii;
         for  (i = 0 ;i < MAXN; ++ i)
        {
            Dis[i] = lmax;
             for  (ii = 0 ;ii < MAXN; ++ ii)
            {
                hash[i][ii] = lmax;
            }
        }
         for  (i = 0 ;i < n; ++ i)
        {
             long  from,to;
            __int64 cost;
            scanf( " %ld %ld %I64d " , & from, & to, & cost);
        
             if  (cost < hash[from][to])
            {
                hash[from][to] = cost;
            }
        }

        Dis[Start] = 0 ;

         long  j,k;
         for  (i = 1 ;i < m; ++ i)
        {
             bool  doit = false ;
             for  (j = 0 ;j < m; ++ j)
            {
                 for  (k = 0 ;k < m; ++ k)
                {
                     if  (hash[j][k] != lmax && Dis[j] < lmax && Dis[j] + hash[j][k] < Dis[k])
                    {
                        Dis[k] = Dis[j] + hash[j][k];
                        doit = true ;
                    }
                }
            }
             if  ( ! doit)
            {
                 break ;
            }
        }

         bool  Y = true ;
         for  (j = 0 ;j < m; ++ j)
        {
             for  (k = 0 ;k < m; ++ k)
            {
                 if  (Dis[j] < lmax && Dis[j] + hash[j][k] < Dis[k])
                {
                    Y = false ;
                     goto  l1;
                }
            }
        }
l1:


         if  (Dis[End] == lmax ||! Y)
        {
            printf( " infinity\n " );
        }
         else
        {
            printf( " %I64d\n " ,Dis[End]);
        }

    }
     return   0 ;
}