Cod sursa(job #937266)
Utilizator | Vlad Negura Opportunity | Data | 10 aprilie 2013 00:30:05 |
---|---|---|---|
Problema | Aria | Scor | 10 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.4 kb |
#include <fstream>
#include <iomanip>
using namespace std;
ifstream fi("aria.in");
ofstream fo("aria.out");
struct point{long double x,y;}a[1000000];
long long n,i;
int main(){
fi >> n;
for (i=1; i<=n; i++) fi >> a[i].x >> a[i].y;
a[n+1]=a[1];
long double rs=0;
for (i=1; i<=n; i++) rs+=(a[i].x*a[i+1].y-a[i+1].x*a[i].y);
fo << setprecision(5) << (long double)rs/2;
return 0;
}