题目： Suppose you are at a party with n people (labeled from 0 to n - 1) and among them, there may exist one celebrity. The definition of a celebrity is that all the other n - 1 people know him/her b

给你一个set<object> 然后给你了个compareTo的方法，可以比较出大小(任意两个objects都能比较出大小，但是这种关系不具有传递性，即A>B,B>C但是A不一定大于C),让你找出set中最大的object，如果不存在，就返回null。int compare(Object o1, Object o2) {return o1.toString().compareTo(o2.toStr