Cod sursa(job #935744)

Utilizator dariusdariusMarian Darius dariusdarius Data 4 aprilie 2013 17:11:32
Problema Aria Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 0.32 kb
Raporteaza aceasta sursa 
#include<stdio.h>
struct Struct
{
	int x,y;
} a[100005];
int main()
{
	freopen("aria.in","r",stdin);
	freopen("aria.out","w",stdout);
	int n,S=0;
	scanf("%d",&n);
	for(int i=1;i<=n;i++)
		scanf("%d%d",&a[i].x,&a[i].y);
	a[0]=a[n];
	for(int i=0;i<n;i++)
		S=S+a[i].x*a[i+1].y-a[i].y*a[i+1].x;
	printf("%.5lf\n",0.5*S);
	return 0;
}