Poj2240 Arbitrage (spfa judgment ring)

Poj2240 Arbitrage (spfa judgment ring)
Arbitrage

Time Limit:1000 MS		Memory Limit:65536 K
Total Submissions:10997		Accepted:4622

Description

Arbitrage is the use of discrepancies in currency exchange rates to transform one unit of a currency into more than one unit of the same currency. for example, suppose that 1 US Dollar buys 0.5 British pound, 1 British pound buys 10.0 French francs, and 1 French franc buys 0.21 US dollar. then, by converting currencies, a clever trader can start with 1 US dollar and buy 0.5*10.0*0.21 = 1.05 US dollars, making a profit of 5 percent.

Your job is to write a program that takes a list of currency exchange rates as input and then determines whether arbitrage is possible or not.

Input

The input will contain in one or more test cases. om the first line of each test case there is an integer n (1 <= n <= 30), representing the number of different currencies. the next n lines each contain the name of one currency. within a name no spaces will appear. the next line contains one integer m, representing the length of the table to follow. the last m lines each contain the name ci of a source currency, a real number rij which represents the exchange rate from ci to cj and a name cj of the destination currency. exchanges which do not appear in the table are impossible.
Test cases are separated from each other by a blank line. Input is terminated by a value of zero (0) for n.

Output

For each test case, print one line telling whether arbitrage is possible or not in the format "Case case: Yes" respectively "Case case: No ".

Sample Input

3USDollarBritishPoundFrenchFranc3USDollar 0.5 BritishPoundBritishPound 10.0 FrenchFrancFrenchFranc 0.21 USDollar3USDollarBritishPoundFrenchFranc6USDollar 0.5 BritishPoundUSDollar 4.9 FrenchFrancBritishPound 10.0 FrenchFrancBritishPound 1.99 USDollarFrenchFranc 0.09 BritishPoundFrenchFranc 0.19 USDollar0

Sample Output

Case 1: YesCase 2: No

Source

The general idea of Ulm Local 1996 is that it is possible to make more money than at the beginning through the exchange rates of different countries. That is, spfa judgment Ring

# Include
 
  
# Include
  
   
# Include
   
    
# Include
    
     
Using namespace std; int n, m; // vector
     
      
Map [33]; // The name Of The storage Country char name [33] [100]; // The exchange rate of the two countries double f [33] [33]; // currency after conversion from the starting country to the current country double price [33]; // inbound int in_degree [33]; // number of incoming queues int sum [33]; // whether the queue bool in_queue [33]; int tonum (char * str) {for (int I = 0; I
      
        S; sum [x] +++; price [x] = 1.0; in_queue [x] = true; s. push (x); while (! S. empty () {int pos = s. front (); s. pop (); in_queue [pos] = false; for (int I = 0; I
       
         In_degree [edge]) {return true ;}}}return false;} int main () {int t = 0; while (~ Scanf ("% d", & n) {if (n = 0) break; memset (in_degree, 0, sizeof (in_degree); memset (name, 0, sizeof (name); memset (map, 0, sizeof (map); memset (f, 0, sizeof (f); for (int I = 0; I <n; I ++) scanf ("% s", name [I]); = "" scanf ("% d", & m ); = "" for (int = "" I = "0; I