CodeForces 706D 字典树+贪心

Datetime:2016-08-23 01:18:00          Topic:          Share

Author has gone out of the stories about Vasiliy, so here is just a formal task description.

You are given q queries and a multiset  A , initially containing only integer  0. There are three types of queries:

  1. " + x" — add integer  x  to multiset  A .
  2. " - x" — erase one occurrence of integer  x  from multiset  A . It's guaranteed that at least one  x  is present in the multiset  A before this query.
  3. " ? x" — you are given integer  x  and need to compute the value  , i.e. the maximum value of bitwise exclusive OR (also know as XOR) of integer  x  and some integer  y  from the multiset  A .

Multiset is a set, where equal elements are allowed.