pku 2240 Arbitrage

#include
#include
char ch[35][35],st[35],en[35];
double c[35][35],dis;
int m,n;
int find(char *d)
{
    int i;
    for(i=1;i<=n;i++)
    if(strcmp(d,ch[i])==0)return i;
    return -1;    
}
int main()
{
    int f,i,j,k,cas=1,b,e;
   while(scanf("%d",&n)&&n)
   {
      for(i=1;i<=n;i++)
      {scanf("%s",ch[i]);
      for(j=1;j<=n;j++)
      c[i][j]=-1.0;
      }
      scanf("%d",&m);
      //memset(c,0,sizeof(c));
      for(i=1;i<=m;i++)
      {
      scanf("%s%lf%s",st,&dis,en); 
      b=find(st);e=find(en);
      c[b][e]=dis;                
      //if(b==e) c[b][e]=1.0;
      }       
      //floyd
      f=0;
      for(k=1;k<=n;k++)
      {
       for(i=1;i<=n;i++)
        for(j=1;j<=n;j++)
          if(c[i][k]>0&&c[k][j]>0&&c[i][k]*c[k][j]>c[i][j])
          {c[i][j]=c[i][k]*c[k][j];}
      for(i=1;i<=n;i++)
      if(c[i][i]>1.0){f=1;break;}      
      }
      printf("Case %d: ",cas++);
      if(f)printf("Yes\n");
      else printf("No\n");  
   }    
}