To find a circuit, from a currency to exchange a circle back to their own, see whether the exchange rate of the product is greater than 1

 
 

  
  

  
To find a circuit, from a currency to exchange a circle back to their own, see whether the exchange rate of the product is greater than 1
  
  

  
Extend the General shortest road bellman, calculate to Dist (n), is counted to the loop
  
  

  
Maxdist (k) [v] = max{maxdist (k-1) [V],maxdist (K-1) [U]*c (U,v)}
  
  

  
#include 
  
  

  
#include 
  
  

  
#include 
  
  

  
#define MAXN 50
  
  

  
#define MAXM 1000
  
  

  
using namespace Std;
  
  

  
struct Exchange
  
  

  
{
  
  

  
int CI,CJ;
  
  

  
Double CIJ;
  
  

  
}EX[MAXM];
  
  

  
Char name[maxn][20],a[20],b[20];
  
  

  
Double X;
  
  

  
int n,m;
  
  

  
Double MAXDIST[MAXN];
  
  

  
int flag;
  
  

  
int kase = 0;
  
  

  
int Readcase ()
  
  

  
{
  
  

  
scanf ("%d", &n);
  
  

  
if (n = = 0)
  
  

  
return 0;
  
  

  
for (int i = 0; i < n; i++)
  
  

  
scanf ("%s", Name[i]);
  
  

  
scanf ("%d", &m);
  
  

  
for (int i = 0; i < m; i++)
  
  

  
{
  
  

  
int q,w;
  
  

  
scanf ("%s%lf%s", a,&x,b);
  
  

  
for (q = 0; strcmp (a,name[q]); q++)
  
  

  
;
  
  

  
for (w = 0; strcmp (b,name[w]); w++)
  
  

  
;
  
  

  
Ex[i].ci = q;
  
  

  
EX[I].CJ = W;
  
  

  
EX[I].CIJ = x;
  
  

  
}
  
  

  
return 1;
  
  

  
}
  
  

  
void Bellman (int v0)
  
  

  
{
  
  

  
Flag = 0;
  
  

  
memset (maxdist,0,sizeof (maxdist));
  
  

  
Maxdist[v0] = 1;
  
  

  
for (int k = 1; k <= N; k++)//1---N
  
  

  
{
  
  

  
for (int i = 0; i < m; i++)
  
  

  
{
  
  

  
if (Maxdist[ex[i].ci]*ex[i].cij > MAXDIST[EX[I].CJ])
  
  

  
MAXDIST[EX[I].CJ] = MAXDIST[EX[I].CI]*EX[I].CIJ;
  
  

  
}
  
  

  
}
  
  

  
if (Maxdist[v0] > 1.0)
  
  

  
flag = 1;
  
  

  
}
  
  

  
int main ()
  
  

  
{
  
  

  
while (Readcase ())
  
  

  
{
  
  

  
for (int i = 0; i < n; i++)
  
  

  
{
  
  

  
Bellman (i);
  
  

  
if (flag)
  
  

  
Break
  
  

  
}
  
  

  
if (flag)
  
  

  
printf ("Case%d:yes\n", ++kase);
  
  

  
Else
  
  

  
printf ("Case%d:no\n", ++kase);
  
  

  
}
  
  

  
}
 
 

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