[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;

}
};