public class Solution{
public boolean isPalindrome(String s){
if(s.isEmpty()){
return true;
}
int head = 0, tail = s.length() - 1;
char cHead, cTail;
while(head <= tail){
cHead = s.charAt(head);
cTail = s.charAt(tail);
if(!Character.isLetterOrDigits(cHead){
head ++;
}
else if(!Character.isLetterOrDigits(cTail)){
tail --;
}
else{
if(Character.toLowerCase(cHead) != Character.toLowerCase(cTail)){
return false;
}
head ++;
tail --;
}
}
return true;
}
}
