Cod sursa(job #1223084)
Utilizator | FMI - Petcu Ion Cristian jean | Data | 25 august 2014 14:02:55 |
---|---|---|---|
Problema | Aria | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include<cstdio>
#include<cmath>
#define NMAX 100010
using namespace std;
double X[NMAX], Y[NMAX], A;
int main() {
freopen("aria.in", "r", stdin);
freopen("aria.out", "w", stdout);
int N;
scanf("%d", &N);
for (int i = 1 ; i <= N ; i++)
scanf("%lf %lf", &X[i], &Y[i]);
X[N + 1] = X[1], Y[N + 1] = Y[1];
for (int i = 1 ; i <= N ; i++)
A += X[i] * Y[i+1] - X[i+1] * Y[i];
printf("%lf\n", fabs(A * 0.5));
return 0;
}