44 lines
981 B
C++
44 lines
981 B
C++
#include <iostream>
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#include <string.h>
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#include <stdio.h>
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#include <algorithm>
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#include <cmath>
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using namespace std;
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const double pi=acos(-1);
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int R,r,H,t,S;
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double getlen(int n,double r)
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{
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return 2.0*r*tan(pi/n);
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}
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int main()
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{
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while(scanf("%d%d%d%d%d",&R,&r,&H,&t,&S)!=EOF)
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{
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double h=(double)H/t,ans=0;
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int limit=100000;
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for(int i=t;i>=1;i--)
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{
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double rr=1.0*(R-r)/t*(i-1)+r;
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int mi=3,ma=limit,mid,num;
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double s;
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while(mi<=ma)
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{
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mid=(mi+ma)>>1;
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double tmp=getlen(mid,rr)*h;
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if(tmp-S>1e-8)
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{
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s=tmp;
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num=mid;
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mi=mid+1;
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}
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else
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ma=mid-1;
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}
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ans+=num*s;
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limit=num;
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}
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printf("%.3lf\n",ans);
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}
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return 0;
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}
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