holiday/8.10/I-Wall/main.cpp

//<2F>ο<EFBFBD><CEBF><EFBFBD><EFBFBD>˵<EFBFBD> 
#include <iostream>
#include <cmath>
#include <cstdio>
#include <algorithm>
#include<stack>
using namespace std;
const double pi=acos(-1.00),eps = 1e-8;//pi3.14~
const int N=1005,inf=0x3f3f3f3f;
double ans=0;
int q[N],n;
struct Point{
    double x,y;
    Point () {}//<2F>޲εĹ<CEB5><C4B9>캯<EFBFBD><ECBAAF>,<2C><><EFBFBD><EFBFBD>ʼ<EFBFBD><CABC><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֵ 
    Point (double xx,double yy) :x(xx),y(yy) {}
    Point friend operator - (Point a,Point b)
    {
    	return Point(a.x-b.x,a.y-b.y);
	}
	double friend operator ^ (Point a,Point b)
    {
    	return a.x*b.y-a.y*b.x;
	}	
	bool friend operator < (Point a,Point b)
	{
		if(a.y==b.y ) return a.x<b.x;
		return a.y<b.y;
	}
}p[N];
//stack<int>s;
int sign(double d)
{
	if(fabs(d)<eps) return 0;
	return d>0? 1:-1;
}
//double cross(double x1, double y1, double x2, double y2)
//{
//	return x1 * y2 - x2 * y1;
//}
double dist(Point a,Point b)
{
	Point c=a-b;
	return sqrt(c.x*c.x+c.y*c.y);//CE double 
}
bool cmp(Point a,Point b)
{
	int s=sign((a-p[1])^(b-p[1]));
	if(s>0||(s==0&&dist(a,p[1])<dist(b,p[1])))return 1;
	else return 0;
}
double Graham()
{
	sort(p+1,p+n+1);
	sort(p+1,p+1+n,cmp);
	int top=3;
	q[1]=1,q[2]=2,q[3]=3;
	for(int i=4;i<=n;i++)
	{
		while(top>1&&sign((p[q[top]]-p[q[top-1]])^(p[i]-p[q[top]]))<=0){
			top--;
		}
		q[++top]=i;
	}
	double res=0;
	for(int i=1;i<top;i++)
	{
		res+=dist(p[q[i]],p[q[i+1]]);
	}
	return res+dist(p[q[1]],p[q[top]]);
}
int main()
{
	int l,minn=1,f,ff,x0,x1,x2,y1,y2,y0;
    scanf("%d%d",&n,&l);
    for(int i=1;i<=n;i++)
    {
        scanf("%lf%lf",&p[i].x,&p[i].y);//&!!!
    }
	printf("%d",(int)(Graham()+pi*2*l+0.5));//(int)()<29>ǵü<C7B5><C3BC><EFBFBD><EFBFBD><EFBFBD> 
	return 0;
}