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P4550 收集邮票

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Baoshuo Ren 2021-07-04 11:17:56 +08:00 committed by Baoshuo Ren
parent 6975e0bf42
commit 6a3848036d
Signed by: baoshuo
GPG Key ID: 70F90A673FB1AB68
1 changed files with 17 additions and 0 deletions
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Luogu/problem/P4550/P4550.cpp Normal file
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#include <bits/stdc++.h>
using namespace std;
int n;
double f[10005], g[10005];
int main() {
cin >> n;
f[n] = g[n] = 0;
for (int i = n - 1; i >= 0; i--) {
f[i] = f[i + 1] + 1.00 * n / (n - i);
g[i] = 1.00 * i / (n - i) * (2 * f[i] + 1) + g[i + 1] + 2 * f[i + 1] + 1;
}
cout << fixed << setprecision(2) << 1.00 * (g[0] + f[0]) / 2 << endl;
return 0;
}