Cod sursa(job #2401979)

Utilizator alex2209alexPavel Alexandru alex2209alex Data 10 aprilie 2019 11:23:29
Problema Aria Scor 0
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.3 kb
Raporteaza aceasta sursa 
#include <fstream>

using namespace std;
ifstream f("aria.in");
ofstream g("aria.out");
int n,a[100001],b[100001],i;
long long sum;
int main(int argc, char *argv[]) {
	f>>n;
	f>>a[1]>>b[1];
	for(i=2;i<=n;i++)
	{
		f>>a[i]>>b[i];
		sum+=(a[i-1]*b[i]-a[i]*b[i-1])/2;
	}
	sum+=(a[n]*b[1]-a[1]*b[n])/2;
	g<<sum;
}