Cod sursa(job #1871151)
Utilizator | Data | 7 februarie 2017 10:45:27 | |
---|---|---|---|
Problema | Aria | Scor | 70 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.51 kb |
#include <iostream>
#include <cstdio>
using namespace std;
int n;
double a;
double x1,y1,x2,y2,xa,ya;
double arie()
{
return (-x2*y1+x1*y2)/2;
}
int main()
{
freopen("aria.in","r",stdin);
freopen("aria.out","w",stdout);
scanf("%d\n", &n);
scanf("%lf %lf", &x1, &y1);
xa=x1, ya=y1;
for(int i=1;i<n;i++)
{
scanf("%lf %lf", &x2, &y2);
a+=arie();
x1=x2, y1=y2;
}
x2=xa, y2=ya;
a+=arie();
printf("%.5f", a);
return 0;
}