Cod sursa(job #1125422)

Utilizator gapdanPopescu George gapdan Data 26 februarie 2014 17:28:40
Problema Aria Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 0.32 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
double x,y,sum,a,b;
int i,n;
int main()
{
    fstream f("aria.in",ios::in);
    fstream g("aria.out",ios::out);
    f>>n;
    f>>x>>y;
    for (i=2;i<=n;++i)
    {
        f>>a>>b;
        sum=sum+(x*b-y*a);
        x=a;
        b=y;
    }
    g<<sum;
    return 0;
}