NYOJ 67 三角形面积

 

#include<iostream>

#include<iomanip>

#include<cmath>

using namespace std;

double segment(double a,double b);

double area(double a,double b,double c);

int main()

{

 int j,i=0;

 double h[10000];

    double x1,y1,x2,y2,x3,y3;

    cin>>x1>>y1>>x2>>y2>>x3>>y3;

        while((x1+x2+x3+y1+y2+y3)!=0)

   {

         double a=segment((x1-x2),(y1-y2));

         double b=segment((x2-x3),(y2-y3));

         double c=segment((x3-x1),(y3-y1));

            h[i]=area(a,b,c);

   i++;

            cin>>x1>>y1>>x2>>y2>>x3>>y3;

   } 

     for(j=0;j<i;j++)

  {

   cout<<setiosflags(ios::fixed)<<setprecision(1);

   cout<<h[j]<<endl;

  }

 return 0; 

}

double segment(double a,double b)

{

 double k=sqrt(a*a+b*b);

 return k;

}

double area(double a,double b,double c)

{

 double s=sqrt((a+b+c)*(a+b-c)*(a+c-b)*(b+c-a))/4;

 return s;

}