Cod sursa(job #990247)
Utilizator | Suzanica Mihu suzanica | Data | 27 august 2013 19:05:55 |
---|---|---|---|
Problema | Aria | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include <stdio.h>
using namespace std;
FILE *f=fopen("aria.in","r"),*g=fopen("aria.out","w");
int n,i;
double x[100004],y[100004],aria;
int main(void)
{
fscanf(f,"%d",&n);
for (i=1;i<=n;i++)
fscanf(f,"%lf%lf",&x[i],&y[i]);
x[n+1]=x[1];
y[n+1]=y[1];
for (i=1;i<=n;i++)
aria=aria+x[i]*y[i+1]-x[i+1]*y[i];
aria/=2;
if (aria<0) aria*=-1;
fprintf(g,"%.5lf",aria);
return 0;
}