public static boolean isPalindrome(String s) {
		// Start typing your Java solution below
		// DO NOT write main() function
		if(s == null || s.isEmpty())
			return true;
		
		char[] strings = s.toCharArray();
		for(int i=0, j=strings.length-1; i<j;){
			if(!isAlphanumeric(strings[i])){
				i++;
				continue;
			}

			if(!isAlphanumeric(strings[j])){
				j--;
				continue;
			}
				
			if(!isEquals(strings[i], strings[j]))
				return false;
			
			i ++;
			j --;
		}

		return true;
	}