Cod sursa(job #1871342)
Utilizator | Data | 7 februarie 2017 11:46:36 | |
---|---|---|---|
Problema | Aria | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.53 kb |
#include <fstream>
#include <iomanip>
using namespace std;
int n;
double a;
double x[100006], y[100006];
double arie(double x1, double x2, double y1, double y2)
{
return (x1*y2-x2*y1)/2;
}
int main()
{
ifstream in ("aria.in");
ofstream out ("aria.out");
in>>n;
for(int i=0;i<n;i++)
{
in>>x[i]>>y[i];
}
x[n]=x[0], y[n]=y[0];
for(int i=0;i<n;i++)
a+=arie(x[i], x[i+1], y[i], y[i+1]);
if(a<0)
a*=(-1);
out<<setprecision(20.5)<<a;
return 0;
}