Cod sursa(job #898670)
Utilizator | Data | 28 februarie 2013 11:19:19 | |
---|---|---|---|
Problema | Aria | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.54 kb |
#include <fstream>
#include <iomanip>
#include <cmath>
#define NM 100010
#define x first
#define y second
using namespace std;
ifstream f("aria.in");
ofstream g("aria.out");
int N;
pair<double, double> V[NM];
double ANS;
int i;
int main ()
{
f >> N;
for (i=1; i<=N; i++)
f >> V[i].x >> V[i].y;
V[N+1]=V[1]; V[0]=V[N];
for (i=1; i<=N; i++)
ANS+=V[i].x*(V[i+1].y-V[i-1].y);
g << fixed << setprecision(4) << fabs(ANS*0.5) << '\n';
f.close();
g.close();
return 0;
}