[leetcode]Valid Palindrome

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

 

For example,
"A man, a plan, a canal: Panama" is a palindrome.
"race a car" is not a palindrome.

Note:
Have you consider that the string might be empty? This is a good question to ask during an interview.

For the purpose of this problem, we define empty string as valid palindrome.

明天就是五一小长假了，突然有点失落呀，每次放假都有点囧~~ 这是一个非常非常无聊的题，符合现在的心情，所以就写写了。。。

 

class Solution {

public:

    bool isPalindrome(string s) {

        // Start typing your C/C++ solution below

        // DO NOT write int main() function

        int p=0, q=s.size()-1;

        

        while(p<q){            

            if(!((s[p] >= 'a' && s[p] <= 'z') || (s[p] >= 'A' && s[p] <= 'Z') ||(s[p] - '0' >= 0 && s[p] -'0'<=9))) {

                p++;

                continue;

            }

            if(!((s[q] >= 'a' && s[q] <= 'z') || (s[q] >= 'A' && s[q] <= 'Z') ||(s[q] - '0' >= 0 && s[q] -'0'<=9))) {

                q--;

                continue;

            }

            

            if(s[p]!=s[q] && s[p]-s[q] != 'A'-'a' && s[p]-s[q] != 'a'-'A') 

                return false;

            p++;

            q--;           

        }

        return true;

        

    }

};