HDU ACM 11 2048 神、上帝以及老天爷

//错排公式  f(n) = (n - 1)(f(n - 1) + f(n - 2)); f(0) = 0, f(1) = 0, f(2) = 1;重要递推

#include <iostream>
using namespace std;
int main()
{
int C;
int n;
cin >> C;
while (C--)
{
cin >> n;
cout << fixed;
cout.precision(2);
double Lu[22];
Lu[1] = 0;
Lu[2] = 1;
for (int i = 3; i < n + 1; i++)
{
Lu[i] = (i - 1) * (Lu[i - 1] + Lu[i - 2]);
}
for (int i = 1; i <= n; i++)
Lu
/= i;
cout << Lu
* 100 << "%" << endl;
}
return 0;
}