Cod sursa(job #2574556)
Utilizator | Data | 5 martie 2020 23:47:27 | |
---|---|---|---|
Problema | Aria | Scor | 70 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.55 kb |
#include <fstream>
#include <iomanip>
using namespace std;
ifstream fin("aria.in");
ofstream fout("aria.out");
const int NMAX = 1e5 + 3;
struct punct
{
double x, y;
};
punct p, f, ant;
int n;
double rez;
inline double arie(punct a, punct b)
{
return a.x * b.y - a.y * b.x;
}
int main()
{
fin >> n;
fin >> f.x >> f.y;
ant = f;
for (int i = 1; i < n; ++i)
{
fin >> p.x >> p.y;
rez += arie(ant, p);
ant = p;
}
rez += arie(ant, f);
rez /= 2;
fout << fixed << setprecision(5) << rez << "\n";
return 0;
}