LeetCode1576. 替换所有的问号

原题链接

class Solution {
public:
    string modifyString(string s) {
        int lens = s.length();
        for(int i = 0; i < lens; ++i) {
            if(s[i] == '?') {
                if(i == 0)
                    s[i] = 'a';
                if(i > 0)
                    s[i] = (s[i-1] -'a'+ 1)%26 + 'a';
                if(i < lens - 1 && s[i] == s[i+1])
                    s[i] = (s[i+1] -'a'+ 1)%26 + 'a';
            }
        }
        return s;
    }
};