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| #include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<ctime>
#include<iomanip>
#include<queue>
#include<stack>
#include<map>
#include<vector>
#define gh() getchar()
#define re register
#define db double
typedef long long ll;
using namespace std;
const int MAXN=4e4+1;
const int dx[]={0,1,-1,1,-1};
const int dy[]={0,1,1,-1,-1};
template<class T>
inline void read(T &x)
{
x=0;
char ch=gh(),t=0;
while(ch<'0'||ch>'9') t|=ch=='-',ch=gh();
while(ch>='0'&&ch<='9') x=(x<<3)+(x<<1)+(ch^48),ch=gh();
if(t) x=-x;
}
template<class T,class ...T1>
inline void read(T &x,T1 &...x1)
{
read(x),read(x1...);
}
template<class T>
inline bool checkMax(T &x,T &y)
{
return x<y?x=y,1:0;
}
template<class T>
inline bool checkMin(T &x,T &y)
{
return x>y?x=y,1:0;
}
int N,cnt;
double len,wid,rth;
struct Point
{
double x,y;
Point operator-(const Point &a)const
{
return {x-a.x,y-a.y};
}
Point(double x=0,double y=0):x(x),y(y){}
}Pt[MAXN],centre[MAXN];
inline double cross(Point a,Point b)
{
return a.x*b.y-a.y*b.x;
}
inline double area(Point a,Point b,Point c)
{
return cross(b-a,c-a);
}
inline Point rotate(Point a,double alph)
{
return {a.x*cos(alph)+a.y*sin(alph),-a.x*sin(alph)+a.y*cos(alph)};
}
double theta[MAXN];
inline void init()
{
for(int i=1;i<=N;++i)
for(int k=1;k<=4;++k)
{
Point dis=rotate({dx[k]*len,dy[k]*wid},-theta[i]);
Pt[++cnt]=Point(centre[i].x+dis.x,centre[i].y+dis.y);
}
}
int stk[MAXN<<1],top;
bool used[MAXN];
inline bool cmp(Point a,Point b)
{
if(a.x==b.x) return a.y<b.y;
return a.x<b.x;
}
inline double getDist(Point a,Point b)
{
return std::sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}
inline void andrew()
{
std::sort(Pt+1,Pt+1+cnt,cmp);
top=0;
for(int i=1;i<=cnt;++i)
{
while(top>=2)
{
double res=area(Pt[stk[top-1]],Pt[stk[top]],Pt[i]);
if(res<0) used[stk[top--]]=0;
else if(res==0) --top;
else break;
}
stk[++top]=i;
used[i]=1;
}
used[1]=0;
for(int i=cnt;i>=1;--i)
{
if(used[i]) continue;
while(top>=2&&area(Pt[stk[top-1]],Pt[stk[top]],Pt[i])<0) --top;
stk[++top]=i;
}
double res=0;
for(int i=2;i<=top;++i) res+=getDist(Pt[stk[i-1]],Pt[stk[i]]);
printf("%.2lf",res+(2*rth*acos(-1)));
}
int main()
{
read(N);
scanf("%lf%lf%lf",&wid,&len,&rth);
wid=(wid-2*rth)/2;
len=(len-2*rth)/2;
for(int i=1;i<=N;++i) scanf("%lf%lf%lf",¢re[i].x,¢re[i].y,&theta[i]);
init();
andrew();
return 0;
}
|