Cod sursa(job #2231759)
Utilizator | Data | 15 august 2018 21:00:56 | |
---|---|---|---|
Problema | Aria | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.47 kb |
#include<iostream>
#include<fstream>
#include<math.h>
using namespace std;
int main(){
ifstream in("aria.in");
FILE *out=fopen("aria.out","w");
int n;
long double xPrev, yPrev, x, y, xF, yF, sol=0;
in>>n>>xPrev>>yPrev;
xF=xPrev; yF=yPrev;
for(int i=1;i<=n-1;i++){
in>>x>>y;
sol+=(xPrev*y-x*yPrev);
xPrev=x; yPrev=y;
}
sol+=(xPrev*yF-xF*yPrev);
sol=sol/2.0;
fprintf(out,"%.5lf",fabs(sol));
in.close(); fclose(out);
return 0;
}