Babaza Game

#include <iostream>
#include <string>
#include <vector>
using namespace std;

int main() {
  string s, t;
  cin >> s >> t;
  int n = s.size();

  bool one = true;
  for (int i = 0; i + 1 < n; i++)
    if (s[i] != t[i] && s[i + 1] != t[i + 1]) one = false;
  if (one) { cout << s << "\n" << t << "\n"; return 0; }

  vector<vector<int>> pr(n, vector<int>(26, -2));
  for (int c = 0; c < 26; c++) pr[0][c] = -1;
  for (int i = 1; i < n; i++)
    for (int c = 0; c < 26; c++)
      for (int p = 0; p < 26; p++) {
        if (pr[i - 1][p] == -2 || p == c) continue;
        if (p != s[i - 1] - 'A' && c != s[i] - 'A') continue;
        if (p != t[i - 1] - 'A' && c != t[i] - 'A') continue;
        pr[i][c] = p;
        break;
      }
  for (int c = 0; c < 26; c++)
    if (pr[n - 1][c] != -2) {
      string u(n, '?');
      for (int i = n - 1, x = c; i >= 0; i--) { u[i] = 'A' + x; x = pr[i][x]; }
      cout << s << "\n" << u << "\n" << t << "\n";
      return 0;
    }

  char x = 'A';
  while (s.find(x) != string::npos || t.find(x) != string::npos) x++;
  string a = s, b = t;
  for (int i = 0; i < n; i += 2) a[i] = b[i] = x;
  cout << s << "\n" << a << "\n" << b << "\n" << t << "\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED