125. 验证回文串

 1 class Solution 
 2 {
 3 public:
 4     bool isPalindrome(string s) 
 5     {
 6         string str;
 7         for(int i = 0;i < s.size();i ++)
 8         {
 9             if(isdigit(s[i])) str.push_back(s[i]);
10             if(isalpha(s[i])) str.push_back(tolower(s[i]));
11         }
12         int n = str.size();
13         for(int i = 0;i < n/2;i ++)
14         {
15             if(str[i] != str[n - 1 - i]) return false;
16         }
17         return true;
18     }
19 };