Cod sursa(job #909759)
Utilizator | Data | 10 martie 2013 16:54:58 | |
---|---|---|---|
Problema | Aria | Scor | 10 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.37 kb |
#include <iostream>
#include <fstream>
using namespace std;
float x[100001],y[100001];
int main()
{ifstream fin("aria.in");
ofstream fout("aria.out");
float s;
int n,i;
fin>>n;
for(i=1;i<=n;i++)
fin>>x[i]>>y[i];
for(i=1,s=0;i<n;i++)
s+=(x[i]*y[i+1]-x[i+1]*y[i]);
s+=x[n]*y[1]-x[1]*y[n];
if(s<0)
fout<<-s/2;
else
fout<<s/2;
return 0;
}