OJ-Problems-Source/HDOJ/4368_autoAC.cpp

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#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;
}