Cod sursa(job #1871330)
Utilizator | Data | 7 februarie 2017 11:40:12 | |
---|---|---|---|
Problema | Aria | Scor | 70 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.49 kb |
#include <fstream>
#include <iomanip>
using namespace std;
int n;
double a;
double x1,y1,x2,y2,xa,ya;
double arie()
{
return (x1*y2-x2*y1);
}
int main()
{
ifstream in ("aria.in");
ofstream out ("aria.out");
in>>n;
in>>x1>>y1;
xa=x1, ya=y1;
for(int i=1;i<n;i++)
{
in>>x2>>y2;
a+=arie();
x1=x2, y1=y2;
}
x2=xa, y2=ya;
a+=arie();
if(a<0)
a*=(-1);
out<<setprecision(20.5)<<a/2;
return 0;
}