Babaza Game

#include <bits/stdc++.h>

using namespace std;

int main()
{
    cin.tie(0)->sync_with_stdio(0);
    string start = "";
    string end = "";
    cin >> start >> end;
    int wordlength = start.size();
    int firstchange = 0;
    cout << start << "\n";
    while(start.compare(end))
    {
        bool notchanged = true;
        set<char> letters = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'};
        for(int i = firstchange; i < wordlength; i++)
        {
            letters.erase(start[i]);
            letters.erase(end[i]);
            if(start[i] != end[i])
            {
                bool canchange = true;
                if(i > 0)
                {
                    if(start[i-1] == end[i]) canchange = false;
                }
                if(i < wordlength-1)
                {
                    if(start[i+1] == end[i]) canchange = false;
                    letters.erase(start[i+1]);
                    letters.erase(end[i+1]);
                }
                if(canchange)
                {
                    if(notchanged) 
                    {
                        notchanged = false;
                        firstchange = i+1;
                    }
                    start[i] = end[i];
                    i++;
                }
                else
                {
                    if(notchanged) 
                    {
                        notchanged = false;
                        firstchange = i+1;
                    }
                    start[i] = *letters.begin();
                    i++;
                }
            }
        }
        if(firstchange >= wordlength) firstchange = 0;
        cout << start << "\n";
    }

}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: TIME LIMIT EXCEEDED

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: WRONG ANSWER