func_code_string: #include <bits/stdc++.h>   using namespace std;   int a[1000005];   int main() {     int n;     long long sum = 0;     cin >> n;     memset(a, -1, sizeof(a));     for (int i = n; i >= 0; i--) {       if (a[i] != -1)         continue;       else {         for (int tt = 1;; tt *= 2) {           if (tt - 1 >= i) {             a[i] = tt - 1 - i;             a[tt - 1 - i] = i;             sum = sum + 2 * (tt - 1);             break;           }         }       }     }     cout << sum << endl;     for (int i = 0; i <= n; i++) {       if (i != 0) printf(   );       printf( %d , a[i]);     }     cout << endl;     return 0;   }   