38 lines
687 B
C++
38 lines
687 B
C++
#include<cstdio>
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#include<cstdlib>
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#include<cstring>
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#include<cmath>
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#include<algorithm>
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using namespace std;
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const int maxn=1510;
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double a[maxn], d[maxn];
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void getd()
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{
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d[1]=0.5;
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for(int i=2; i<maxn; i++)
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d[i]=d[i-1]*(2*i-1)/(2*i);
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}
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void geta()
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{
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a[0]=1.0;
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for(int i=1; i<maxn; i++)
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a[i]=a[i-1]+2*d[i];
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}
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int main()
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{
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getd();
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geta();
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int t, ca=1, n;
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scanf("%d", &t);
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while(t-->0)
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{
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scanf("%d", &n);
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printf("Case %d: ", ca++);
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if(n&1)
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printf("%.6lf\n", a[n/2]);
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else
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printf("%.6lf\n", (a[(n-1)/2]+a[(n+1)/2])*0.5);
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}
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return 0;
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}
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