1328. Break a Palindrome

class Solution {
public:
    string breakPalindrome(string palindrome)
    {
        int n = palindrome.size();
        if (n == 1)
        {
            return "";
        }

        for (int i = 0; i < n / 2; ++i)
        {
            if (palindrome[i] != 'a')
            {
                palindrome[i] = 'a';
                return palindrome;
            }
        }
        palindrome.back() = 'b';
        return palindrome;
    }
};

• T: $O(N)$
• S: $O(N)$