Cod sursa(job #2083169)
Utilizator | Data | 7 decembrie 2017 09:21:36 | |
---|---|---|---|
Problema | Aria | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.5 kb |
#include <cstdio>
using namespace std;
double x[100005], y[100005];
int main() {
freopen("aria.in", "r", stdin);
freopen("aria.out", "w", stdout);
int n;
double sum = 0;
scanf("%d", &n);
for(int i = 1; i <= n; ++ i) {
scanf("%lf%lf", &x[i], &y[i]);
}
for(int i = 2; i <= n; ++ i) {
sum += (x[i - 1] * y[i] - x[i] * y[i - 1]) / 2;
}
sum += (x[n] * y[1] - x[1] * y[n]) / 2;
printf("%.5lf\n", sum);
return 0;
}