64 lines
1.8 KiB
C++
64 lines
1.8 KiB
C++
#include<stdio.h>
|
|
#include<math.h>
|
|
#define eps 1e-5
|
|
#define PI 3.1415926535897932384626
|
|
int n,a[10001];
|
|
double angle;
|
|
int i,j,k,maxtop;
|
|
double dis[10001],t,top,ans,low,h;
|
|
int main()
|
|
{
|
|
while(~scanf("%d%lf",&n,&angle))
|
|
{
|
|
if(angle<-eps) for(i=n-1;i>=0;i--) scanf("%d",&a[i]);
|
|
else for(i=0;i<n;i++) scanf("%d",&a[i]);
|
|
if(angle<-eps) angle=-angle;
|
|
angle=PI*angle/180.0;
|
|
t=-1;ans=0;
|
|
for(i=0;i<n;i++)
|
|
{
|
|
dis[i]=((i+1)*tan(angle)+a[i]*1.0)/sqrt(tan(angle)*tan(angle)+1);
|
|
if(t<dis[i]){t=dis[i];maxtop=i;}
|
|
}
|
|
for(i=0;i<maxtop;i++)
|
|
{
|
|
top=a[i];
|
|
for(j=i+1;j<=maxtop;j++)
|
|
{
|
|
if(dis[j]>dis[i]+eps)
|
|
{
|
|
if(dis[j]-sin(angle)>dis[i]+eps)
|
|
{
|
|
top-=(j-i-1)*1.0*tan(angle);
|
|
ans+=(j-i-1)*(j-i-1)*0.5*tan(angle);
|
|
}
|
|
else
|
|
{
|
|
top-=(a[i]-a[j])*1.0;
|
|
ans+=(a[i]-a[j])*(a[i]-a[j])*0.5/tan(angle);
|
|
}
|
|
for(k=i+1;k<j;k++)
|
|
ans+=(top-a[k])*1.0;
|
|
i=j-1;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
for(i=n-1;i>maxtop;i--)
|
|
{
|
|
for(j=i-1;j>=maxtop;j--)
|
|
{
|
|
h=i-j;
|
|
low=h*tan(angle)-(a[j+1]-a[i]);
|
|
top=(h-1)*tan(angle)-(a[j+1]-a[i]);
|
|
ans+=(top+low)/2.0;
|
|
if(dis[j]>dis[i]+eps)
|
|
break;
|
|
}
|
|
i=j+1;
|
|
}
|
|
printf("%.2lf\n",ans);
|
|
}
|
|
return 0;
|
|
}
|