Cod sursa(job #1465272)
Utilizator | Stoiean Tudor tudor00 | Data | 26 iulie 2015 21:20:29 |
---|---|---|---|
Problema | Aria | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include <fstream>
#define NMAX 100010
using namespace std;
ifstream in("aria.in");
ofstream out("aria.out");
int n,i;
int x[NMAX],y[NMAX];
long long s=0;
int main()
{
in>>n;
for(i=1;i<=n;i++)
{
in>>x[i]>>y[i];
}
for(i=1;i<n;i++)
{
s+=(x[i]*y[i+1]-y[i]*x[i+1])/2;
}
s+=(x[n]*y[1]-y[n]*x[1])/2;
out<<s;
in.close();
out.close();
return 0;
}