Cod sursa(job #1905784)

Utilizator usureluflorianUsurelu Florian-Robert usureluflorian Data 6 martie 2017 10:51:18
Problema Aria Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.33 kb
Raporteaza aceasta sursa 
#include <bits/stdc++.h>
using namespace std;
ifstream f ("aria.in");
ofstream g ("aria.out");
double a[100001],b[100001],s;
int n,i;
int main()
{
    f>>n;
    for(i=1;i<=n;++i) f>>a[i]>>b[i];
    a[n+1]=a[1]; b[n+1]=b[1];
    for(i=1;i<=n;++i) s+=a[i]*b[i+1]-a[i+1]*b[i];
    g<<fixed<<setprecision(6)<<s/2;
    return 0;
}