31 lines
561 B
C++
31 lines
561 B
C++
#include<stdio.h>
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#include<math.h>
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double cal(double r1,double r2,double dx)
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{
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return sqrt(r1*r1-dx*dx)*sqrt(r2*r2-dx*dx);
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}
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double fun(double r1,double r2)
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{
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int n=1000000;
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double dx=(r1<r2?r1:r2)/n;
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double pi=3.141592653;
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double v=0;
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for(int i=0;i<n;i++)
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{
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v+=cal(r1,r2,(double)dx*i+dx/2);
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}
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return v*8*dx;
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}
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int main()
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{
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int t;
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double r1,r2;
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scanf("%d",&t);
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while(t--)
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{
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scanf("%lf%lf",&r1,&r2);
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printf("%.2lf\n",fun(r1,r2));
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}
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return 0;
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}
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