func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, k;   double f[2][810];   int main() {     scanf( %d%d , &n, &k);     for (int i = 1; i * i <= n; ++i) f[0][i] = 0;     int st = min(max(800.0, sqrt(n)), 1.0 * n);     int c = 0;     for (int i = 1; i <= n; ++i) {       c ^= 1;       for (int j = 1; j <= st; ++j) {         f[c][j] = 1.0 * (k - 1) / k * f[c ^ 1][j] +                   1.0 * j / k / (j + 1) * f[c ^ 1][j] +                   1.0 / k / (j + 1) * (f[c ^ 1][j + 1] + (1.0 + j) * j / 2.0 + j);         if (f[c][j] <= 1e-100) f[c][j] = 0;       }     }     printf( %.10lf , f[c][1] * k);     return 0;   }   