64 lines
1.4 KiB
C++
64 lines
1.4 KiB
C++
#include <iostream>
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#include <cstdio>
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#include <cstring>
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#include <string>
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#include <cstdlib>
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#include <cmath>
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#include <vector>
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#include <list>
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#include <deque>
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#include <queue>
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#include <iterator>
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#include <stack>
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#include <map>
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#include <set>
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#include <algorithm>
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#include <cctype>
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using namespace std;
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#define si1(a) scanf("%d",&a)
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#define si2(a,b) scanf("%d%d",&a,&b)
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#define sd1(a) scanf("%lf",&a)
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#define sd2(a,b) scanf("%lf%lf",&a,&b)
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#define ss1(s) scanf("%s",s)
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#define pi1(a) printf("%d\n",a)
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#define pi2(a,b) printf("%d %d\n",a,b)
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#define mset(a,b) memset(a,b,sizeof(a))
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#define forb(i,a,b) for(int i=a;i<b;i++)
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#define ford(i,a,b) for(int i=a;i<=b;i++)
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typedef long long LL;
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const int N=100005;
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const int INF=0x3f3f3f3f;
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const double PI=acos(-1.0);
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const double eps=1e-8;
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double H,D,V,R;
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double xiaohao(double r)
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{
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double xh=0;
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xh+=H*R*R*acos((R-r)/R)/3.0;
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xh-=2.0/3.0*(R-r)*H*sqrt(R*R-(R-r)*(R-r));
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xh+=1.0/3.0*(R-r)*(R-r)*(R-r)*H/R*log((R+sqrt(R*R-(R-r)*(R-r)))/(R-r));
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return xh;
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}
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int main()
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{
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int i,j,T;
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si1(T);
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while(T--)
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{
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sd1(H);sd2(D,V);
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R=D/2;
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double low=0,up=R,m,tmp;
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while((up-low)>eps)
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{
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m=(up+low)/2;
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double tmp=xiaohao(m);
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if(tmp>V)
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up=m;
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else
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low=m;
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}
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printf("%.5f\n",D-m);
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}
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return 0;
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}
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