389. 找不同

class  {
    public char findTheDifference(String s, String t) {
		char tmp = 0x00;
        for(int i = 0;i < s.length();i++) {
        	tmp =(char)(tmp ^ s.charAt(i));
        }
            
        for(int i = 0;i < t.length();i++) {
            tmp = (char)(tmp ^ t.charAt(i));
        }
        
        return tmp;
    }
}