40 lines
781 B
C++
40 lines
781 B
C++
#include<stdio.h>
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#include<string.h>
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#include<math.h>
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#define pi acos(-1.0)
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#define eps 1e-7
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int main()
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{
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int n,t,f,i,r,pep;
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double s[10005];
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double max,min,mid;
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scanf("%d",&t);
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while(t--)
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{
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min=0;max=0;
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scanf("%d%d",&n,&f);
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f++;
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for(i=0; i<n; i++)
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{
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scanf("%d",&r);
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s[i]=pi*r*r;
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if(max<s[i]) max=s[i];
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}
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while(max-min>eps)
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{
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mid=(max+min)/2;
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pep=0;
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for(i=0;i<n;i++)
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{
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pep+=(int)(s[i]/mid);
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}
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if(pep>=f)
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min=mid;
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else
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max=mid;
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}
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printf("%.4lf\n",mid);
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}
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return 0;
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}
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