func_code_string: #include <bits/stdc++.h>   const int MAXN = 5E5 + 10;   int n;   int a[MAXN << 1];   int main() {     scanf( %d , &n);     for (int i = 1; i < n; ++i) {       int t = i + 1 >> 1;       if (i & 1)         a[t] = a[n - t + 1] = i;       else         a[n + t] = a[n * 2 - t] = i;     }     a[2 * n] = n;     if (n & 1)       a[n + 1 >> 1] = n;     else       a[n + (n >> 1)] = n;     for (int i = 2 * n; i > 0; --i) printf( %d%c , a[i],   n  [i > 1]);     return 0;   }   