Cod sursa(job #898526)
Utilizator | Albu Alexandru alexalbu95 | Data | 28 februarie 2013 10:35:18 |
---|---|---|---|
Problema | Aria | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.54 kb |
#include <fstream>
#include <cstdio>
using namespace std;
ifstream f("aria.in");
ofstream g("aria.out");
struct point{
double x, y;
}v[100001];
double s;
int n;
void read()
{
f>>n;
for(int i=0; i<n; ++i) f>>v[i].x>>v[i].y;
v[n].x=v[0].x;
v[n].y=v[0].y;
v[n+1].x=v[1].x;
v[n+1].y=v[1].y;
}
void solve()
{
int i;
for(i=1; i<=n; ++i)
s += v[i].x*(v[i+1].y-v[i-1].y);
}
int main()
{
freopen("aria.out", "w", stdout);
read();
solve();
printf("%.4f", s/2.0);
}