题目

class Solution 
{
    public String modifyString(String ss)
    {
        char[] s = ss.toCharArray();
        int n = s.length;
        
        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 String.valueOf(s);
    }
}