1020.cpp

平时acm训练时ac的源代码

#include <iostream.h>
#include <math.h>
#include <stdio.h>
int main()
{
	double sum;
	double x0,y0,x1,y1,x2,y2,l,r,m;
	int n,i;
	cin>>n>>r;
	sum=2*3.1415926*r;
	cin>>x0>>y0;
	x2=x0;
	y2=y0;
	
	for(i=1;i<n;i++)
	{
		cin>>x1>>y1;
		m=(x0-x1)*(x0-x1)+(y0-y1)*(y0-y1);
		l=sqrt(m);
		sum+=l;
		x0=x1;
		y0=y1;
	}

	m=(x2-x0)*(x2-x0)+(y2-y0)*(y2-y0);
	l=sqrt(m);
	sum+=l;
	printf("%.2lf",sum);
}