POJ 1860 Currency Exchange

//Time 16ms, Memory 244K

#include<iostream>
#include<cstring>
using namespace std;
int cnt,n,m,s;
double v;
struct point
{
    int a,b;
    double r,c;
    point(int a=0,int b=0,double r=0.0,double c=0.0):a(a),b(b),r(r),c(c){}
}p[201];
int bellman()
{
    int i,j;
    int flag;
    double dis[101];
    memset(dis,0,sizeof(dis));
    dis[s]=v;
    for(i=1;i<n;i++)
    {
        flag=0;
        for(j=0;j<cnt;j++)
        {
            if(dis[p[j].b]<(dis[p[j].a]-p[j].c)*p[j].r)
            {
                dis[p[j].b]=(dis[p[j].a]-p[j].c)*p[j].r;flag=1;
            }
        }
        if(!flag) break;
    }
    for(j=0;j<cnt;j++)
    {
        if(dis[p[j].b]<(dis[p[j].a]-p[j].c)*p[j].r) return 1;
    }
    return 0;
}
int main()
{
    int i,a,b;
    double r1,r2,c1,c2;
    cin>>n>>m>>s>>v;
    cnt=0;
    for(i=0;i<m;i++)
    {
        cin>>a>>b>>r1>>c1>>r2>>c2;
        p[cnt++]=point(a,b,r1,c1);
        p[cnt++]=point(b,a,r2,c2);
    }
    if(bellman()) cout<<"YES"<<endl;
    else cout<<"NO"<<endl;
    return 0;
}