LeetCode_ValidPalindrome.cpp

class Solution {
public:
    bool isPalindrome(string s) {
        if(s.empty())
        {
            return true;
        }
        int i = 0;
        int j = s.length()-1;
        while(i < j)
        {
            while(i < s.length() && !isalnum(s[i]))
            {
                i++;
            }
            while(j > 0 && !isalnum(s[j]))
            {
                j--;
            }
            if(i < s.length() && j > 0 && tolower(s[i]) != tolower(s[j]))
            {
                return false;
            }
            i++;
            j--;
        }
        return true;
    }
};