Super easy solution, O(n), beats 100%
\npublic String modifyString(String s) {\n    if (s == null || s.isEmpty()) return "";\n    \n    char[] chars = s.toCharArray();\n    for (int i=0; i<chars.len
```\npublic String modifyString(String s) {\n    if (s == null || s.isEmpty()) return "";\n    \n    char[] chars = s.toCharArray();\n    for (int i=0; i<chars.length; i++) {\n        if (chars[i] == \'?\') {\n            for (char j=\'a\'; j<=\'z\'; j++) {\n                chars[i] = j;\n                if (i>0 && chars[i-1] == j) continue;\n                if(i<chars.length-1 && chars[i+1] == j) continue;\n                break;\n            }\n        }\n    }\n    \n    return new String(chars);\n}\n```
['Java']