Cod sursa(job #1472418)

Utilizator BlaugranasEnal Gemaledin Blaugranas Data 17 august 2015 04:33:27
Problema Aria Scor 100
Compilator c Status done
Runda Arhiva educationala Marime 0.32 kb
Raporteaza aceasta sursa 
#include<stdio.h>
int n,i;
long double x[100007],y[100007],s;
int main() {
    freopen("aria.in","r",stdin),freopen("aria.out","w",stdout),scanf("%d",&n);
    for(i=0;i<n;i++)
        scanf("%Lf%Lf",x+i,y+i);
    for(x[n]=x[0],y[n]=y[0],i=0;i<n;i++)
        s+=(x[i]*y[i+1]-x[i+1]*y[i])/2;
    printf("%.5Lf",s);
}