Arbitrage - poj 2240 (Bellman-ford)

 1 #include <iostream>
 2 #include<map>
 3 #include<string.h>
 4 using namespace std;
 5 struct edge{
 6     int u,v;
 7     float rate;
 8 } e[40*40];
 9 int cur_num,edge_num;
10 float dis[40];
11 map<string,int> mp;
12 int Bellman_ford(int c){
13     memset(dis,0,30*sizeof(float));
14     dis[c]=1.0;
15     for(int i=0;i<cur_num;i++){
16         for(int j=0;j<edge_num;j++){
17             if(dis[e[j].v]<dis[e[j].u]*e[j].rate){
18                 dis[e[j].v]=dis[e[j].u]*e[j].rate;
19             }
20         }
21     }
22     if(dis[c]>1.0)
23         return 1;
24     else
25         return 0;
26 }
27 int main() {
28     int count=0;
29     cin>>cur_num;
30     while(cur_num){
31         mp.clear();
32         for(int i=0;i<cur_num;i++){
33             string s;
34             cin>>s;
35             mp[s]=i;
36         }
37         cin>>edge_num;
38         for(int i=0;i<edge_num;i++){
39             string s1,s2;
40             float rate;
41             cin>>s1>>rate>>s2;
42             e[i].u=mp[s1];
43             e[i].v=mp[s2];
44             e[i].rate=rate;
45         }
46         int flag=0;
47         for(int i=0;i<cur_num;i++){
48             flag=Bellman_ford(i);
49             if(flag)
50                 break;
51         }
52 
53         if(flag)
54             cout<<"Case "<<++count<<": Yes"<<endl;
55         else
56             cout<<"Case "<<++count<<": No"<<endl;
57         cin>>cur_num;
58     }
59     return 0;
60 }