public class Solution {
public boolean isPalindrome(String s) {
int start = 0;
int end = s.length() - 1;
char c1, c2;
while (start <= end) {
c1 = s.charAt(start);
c2 = s.charAt(end);
if (!Character.isLetterOrDigit(c1)) {
start++;
} else if (!Character.isLetterOrDigit(c2)) {
end--;
} else {
if (Character.toLowerCase(c1) != Character.toLowerCase(c2)) {
return false;
}
start++;
end--;
}
}
return true;
}
}