67 lines
1.6 KiB
C++
67 lines
1.6 KiB
C++
#include <iostream>
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#include <cstdio>
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#include <cmath>
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#include <cstring>
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#include <algorithm>
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#include <map>
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using namespace std;
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const double pi=3.14159265358979,eps=1e-7;
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double r,hr,hz;
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double f(double n)
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{
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return pi*(r*r-n*n);
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}
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double simpson(double a,double b)
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{
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return (b-a)/6.0*(f(a)+4*f((a+b)/2.0)+f(b));
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}
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double cal(double a,double b)
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{
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double sum=simpson(a,b),mid=(a+b)/2.0;
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double t=simpson(a,mid)+simpson(mid,b);
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if(fabs(t-sum)<eps) return sum;
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return cal(a,mid)+cal(mid,b);
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}
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int main()
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{
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while(scanf("%lf%lf%lf",&r,&hr,&hz)!=EOF)
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{
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double v=0,hv=0;
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if(hr>=r&&hz>=r)
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{
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v=4.0/3.0*pi*r*r*r;
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hv=2*pi*hr*hr*hz;
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printf("%.6lf\n",v/hv);
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continue;
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}
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if(hr>=r&&hz<r)
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{
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v=4.0/3.0*pi*r*r*r;
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double t=2*cal(hz,r);
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hv=2*pi*hr*hr*hz;
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printf("%.6lf\n",(v-t)/(hv+t));
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continue;
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}
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if(r*r>=hr*hr+hz*hz)
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{
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v=4.0/3.0*pi*r*r*r;
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hv=2*pi*hr*hr*hz;
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printf("%.6lf\n",hv/v);
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continue;
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}
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if(hr<r&&hz>=r)
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{
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v=4.0/3.0*pi*r*r*r;
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double t=2*cal(sqrt(r*r-hr*hr),r)+2*sqrt(r*r-hr*hr)*pi*hr*hr;
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hv=2*pi*hr*hr*hz;
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printf("%.6lf\n",t/(hv+v-t));
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continue;
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}
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v=4.0/3.0*pi*r*r*r;
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hv=2*pi*hr*hr*hz;
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double t=2*cal(sqrt(r*r-hr*hr),hz)+2*sqrt(r*r-hr*hr)*pi*hr*hr;
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printf("%.6lf\n",t/(hv+v-t));
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}
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return 0;
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}
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