func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     srand(time(NULL));     int t;     cin >> t;     while (t--) {       int n;       cin >> n;       unordered_map<string, int> codes;       vector<string> v(n);       for (int i = 0; i < n; i++) {         string x;         cin >> x;         v[i] = x;         codes[x]++;       }       int ans = 0;       vector<string> anss;       for (int i = 0; i < n; i++) {         if (codes[v[i]] > 1) {           ans++;           string x = v[i];           while (codes[x] >= 1) {             x = v[i];             int pos = rand() % 4;             char digit = (char)( 0  + (rand() % 10));             x[pos] = digit;           }           codes[x] = 1;           codes[v[i]]--;           anss.push_back(x);         } else           anss.push_back(v[i]);       }       cout << ans <<   n ;       for (auto a : anss) cout << a <<   n ;     }     return 0;   }   