POJ 2240 Arbitrage

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <vector>
#include <queue>
#include <map>
#include <set>
#include <stack>
#include <algorithm>
using namespace std;

typedef long long LL;
const int N = 110;
const int inf = 1e7+7;
const double PI = acos(-1.0);
const double eps = 1e-6 ;

int n , m ;
struct node {
    int v ;
    double w ;
    node(){}
    node( int a , double b ) { v = a , w = b ; }
};

vector<node>g[N];
map<string,int>mp;
string str1 , str2 ;
bool vis[N] , inq[N] ;
double dis[N];
int in_cnt[N];

bool spfa( int s ) {

    queue<int>que;
    for( int i = 0 ; i <= n ; ++i ) dis[i] = 0.0 , in_cnt[i] = 0 , inq[i] = false;
    dis[s] = 1.0 ; inq[s] = true ; que.push(s);
    while( !que.empty() ) {
        int u = que.front() ; que.pop();
        inq[u] = false , vis[u] = true ;
        for( int i = 0 ; i < g[u].size() ; ++i ) {
            int v  = g[u][i].v ; double w = g[u][i].w ;
            if( dis[u] * w > dis[v] ) {
                dis[v] = dis[u] * w ;
                if( !inq[v] ) {
                    in_cnt[v] ++ ;
                    if( in_cnt[v] >= n ) return false;
                    inq[v] = true; que.push(v);
                }
            }
        }
    }
    return true;
}

void run()
{
    double w ;
    mp.clear(); for( int i = 0 ; i <= n ; ++i )g[i].clear();
    for( int i = 1 ; i <= n ; ++i ){
        cin >> str1 , mp[str1] = i ;
    }
    cin >> m ;
    while( m-- ) {
        cin >> str1 >> w >> str2 ;
        int u = mp[str1]  , v = mp[str2] ;
        g[u].push_back( node(v,w) );
    }
    memset(vis,false,sizeof vis);
    bool tag = false ;
    for( int i = 1 ; i <= n ; ++i ) if( !vis[i] ) {
        if( !spfa(i) ) { tag = true ; break ; }
    }
    if( tag ) cout << "Yes" <<endl;
    else cout << "No" << endl;
}

int main()
{
    #ifdef LOCAL
        freopen("in.txt","r",stdin);
    #endif // LOCAL
    ios::sync_with_stdio(false);
    int cas = 1 ;
    while( cin >> n && n ){
        cout << "Case "<<cas++ <<": ";run();
    }
}