func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 1e4 + 100;   int n, k;   char str[N];   bool f[N];   int main() {     scanf( %s , str + 1), n = strlen(str + 1);     while (1 << k < n) ++k;     if (1 << k > n) --k;     memset(f, 1, sizeof(f));     for (int i = 1; i <= n - (1 << k) + 1; ++i) {       char ch =  z ;       for (int s = 0; s < 1 << k; ++s)         if (f[s])           for (int t = 0; t < k; ++t) f[s | (1 << t)] = 1;       for (int s = 0; s < 1 << k; ++s)         if (f[s]) ch = min(str[i + s], ch);       for (int s = 0; s < 1 << k; ++s)         if (str[i + s] != ch) f[s] = 0;       putchar(ch);     }     return 0;   }   