2812.cpp

这些是我到目前在PKU上做出的题目

#include <iostream.h>
#include <stdio.h>

int i,j,n;
double l,x,y,x1,x2,y1,y2,s;

int main()
{
	cin>>n;
	while (n>=3)
	{
		s=0;
		cin>>x>>y;
		x1=x;y1=y;
		for (i=2;i<=n;i++)
		{
			cin>>x2>>y2;
			s=s-0.5*(x1*y2-y1*x2);
			x1=x2;y1=y2;
		}
		s=s-0.5*(x1*y-y1*x);
		cin>>l;
		l=l/s;
		printf("BAR LENGTH: %.2f\n",l);
		cin>>n;
	}
	return 0;
}