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 <stdio.h> 2 #include <string.h> 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 }