func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long int N = 1000000000;   int main(int argc, char const *argv[]) {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     int t;     cin >> t;     while (t-- > 0) {       int n;       cin >> n;       string s, s1;       cin >> s >> s1;       int x = 0;       int op = 0;       vector<int> opr;       for (int i = n - 1; i >= 0; i--) {         if (op % 2 == 0) {           if (s[x + i] == s1[i]) continue;           if (s[x] != s[x + i]) opr.push_back(1);           opr.push_back(i + 1);           op++;           x = x + i;         } else {           char c = s[x - i] ==  0  ?  1  :  0 ;           char c1 = s[x] ==  0  ?  1  :  0 ;           if (c == s1[i]) continue;           if (c != c1) opr.push_back(1);           opr.push_back(i + 1);           op++;           x = x - i;         }       }       cout << opr.size() <<    ;       for (auto i : opr) cout << i <<    ;       cout << endl;     }   }   