Python Easy Solution
Code\n\nclass Solution:\n    def modifyString(self, s: str) -> str:\n        new=s\n        for i in range(len(s)):\n            if new[i]=="?":\n              
# Code\n```\nclass Solution:\n    def modifyString(self, s: str) -> str:\n        new=s\n        for i in range(len(s)):\n            if new[i]=="?":\n                if len(new)==1:\n                    return "p"\n                if i==0:\n                    lis=[new[i+1]]\n                if i==len(s)-1:\n                    lis=[new[i-1]]\n                else:\n                    lis=[new[i-1],new[i+1]]\n                n="a"\n                while(n in lis):\n                    n=chr(ord(n)+1)                    \n                new=new[:i]+n+new[i+1:]\n        return new\n```
['Python3']