【算法】模拟算法——替换所有的问号(easy)

class Solution {
public:
    string modifyString(string s) 
    {
        int n = s.size();
        
        for(int i = 0; i < n; i++)
        {
            if(s[i] == '?')
            {
                for(char ch = 'a'; ch <= 'z'; ch++)
                {
                    if((((i == 0) || ch != s[i-1]) && ((i == n-1) || ch != s[i+1])))
                    {
                        s[i] = ch;
                        break;
                    }
                }
            }
        }
        return s;
    }
};