同样是套汇问题，这题要简单些，我为了多练，换成Floyd算法了。Floyd最大的优点就是写起来简单。

1 #include 
     
       2 #include 
      
        3 int m,n,cas=1; 4 char name[35][40]; 5 double rate[30][30]; 6 int find(char *s) 7 { 8     for(int i = 0; i < n; i++) 9         if(!strcmp(s,name[i]))10             return i;11     return -1;12 }13 bool Floyd()14 {15     int i,j,k;16     for(k = 0; k < n; k++)17         for(i = 0; i < n; i++)18             for(j = 0; j < n; j++)19                 if(rate[i][k] * rate[k][j] > rate[i][j])20                     rate[i][j] = rate[i][k] * rate[k][j];21     return (rate[0][0] > 1) ?1 :0 ;22 }23 int main()24 {25     int i;26     char t1[40],t2[40];27     double r;28     while(scanf("%d",&n),n)29     {30         memset(rate,0,sizeof(rate));31         for(i = 0; i < n; i++)32             scanf("%s",name[i]);33         scanf("%d",&m);34         for(i = 0; i < m; i++)35         {36             scanf("%s%lf%s",t1,&r,t2);37             rate[find(t1)][find(t2)] = r;38         }39         if(Floyd())40             printf("Case %d: Yes\n",cas++);41         else printf("Case %d: No\n",cas++);42     }43     return 0;44 }