Cod sursa(job #2424509)
Utilizator | Data | 23 mai 2019 09:48:53 | |
---|---|---|---|
Problema | Aria | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include<fstream>
#include<iomanip>
using namespace std;
ifstream cin("aria.in");
ofstream cout("aria.out");
#define maxn 100005
int n;
long double sol=0,m[2][maxn];
int main(){
cin>>n;
for(int i=1; i<=n; i++)
cin>>m[0][i]>>m[1][i];
m[0][n+1]=m[0][1];
m[1][n+1]=m[1][1];
for(int i=1; i<=n; i++)
sol+=(m[0][i]*m[1][i+1]-m[0][i+1]*m[1][i]);
cout<<fixed<<setprecision(6)<<sol/2.0;
}