Cod sursa(job #1005268)
Utilizator | Gemene Cozmin cozmin97 | Data | 4 octombrie 2013 17:21:45 |
---|---|---|---|
Problema | Aria | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.53 kb |
#include <fstream>
#define In "aria.in"
#define Out "aria.out"
#define Nmax 100005
using namespace std;
struct Punct
{
double dx,dy;
};
Punct a[Nmax];
double aria;
int main()
{
int i,n;
freopen(In,"r",stdin);
freopen(Out,"w",stdout);
scanf("%d",&n);
for(i=1;i<=n;i++)
scanf("%lf %lf",&a[i].dx,&a[i].dy);
a[0] = a[n];
for(i=0;i<n;i++)
aria+=a[i].dx*a[i+1].dy-a[i].dy*a[i+1].dx;
if(aria<0)
aria*=-1;
aria/=2;
printf("%lf\n",aria);
return 0;
}