Cod sursa(job #947436)
Utilizator | Marin Tiberiu tibi9876 | Data | 7 mai 2013 15:05:12 |
---|---|---|---|
Problema | Aria | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include<fstream>
#include<iomanip>
using namespace std;
double x[100002],y[100002],ar;
int i,n;
int main()
{
ifstream f("aria.in");
ofstream g("aria.out");
f >> n;
for (i=1;i<=n;i++)
f >> x[i] >> y[i];
ar=0;
x[0]=x[n];y[0]=y[n];
x[n+1]=x[1];y[n+1]=y[1];
for (i=1;i<=n;i++)
{
ar+=x[i]*y[i+1];
ar-=x[i]*y[i-1];
}
if (ar<0)
ar*=-1;
ar/=2;
g << setprecision(6) << fixed << ar;
return 0;
}