LeetCode1576. 替换所有的问号

 1 class Solution {
 2 public:
 3     string modifyString(string s) {
 4         int lens = s.length();
 5         for(int i = 0; i < lens; ++i) {
 6             if(s[i] == ‘?‘) {
 7                 if(i == 0)
 8                     s[i] = ‘a‘;
 9                 if(i > 0)
10                     s[i] = (s[i-1] -‘a‘+ 1)%26 + ‘a‘;
11                 if(i < lens - 1 && s[i] == s[i+1])
12                     s[i] = (s[i+1] -‘a‘+ 1)%26 + ‘a‘;
13             }
14         }
15         return s;
16     }
17 };