Cod sursa(job #918430)
Utilizator | Data | 18 martie 2013 21:11:36 | |
---|---|---|---|
Problema | Aria | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.42 kb |
#include <cstdio>
using namespace std;
int x[100010],y[100010];
int main()
{
freopen("aria.in","r",stdin);
freopen("aria.out","w",stdout);
int n,i;
double aria=0;
scanf("%d",&n);
for(i=1;i<=n;++i)
scanf("%d%d",&x[i],&y[i]);
for(i=1;i<n;i++)
aria+=(x[i]*y[i+1]-x[i+1]*y[i]);
aria+=(x[n]*y[1]-x[1]*y[n]);
aria/=2;
printf("%.5lf",aria);
return 0;
}