Codeforces Round #367 (Div. 2) D Vasiliy's Multiset（字典树）

思路：三个操作，增加删除和查找异或最大的，和去年长春区域赛的一道字典树基本一样...

#include<bits/stdc++.h>using namespace std;const int maxn = 3*1e6+7;struct Tree{int Next[maxn][2];int val[maxn];int L,root;void init(){L=0;root = newnode();}int newnode(){for(int i = 0;i<2;i++)Next[L][i]=-1;val[L++]=0;return L-1;}void insert(int va){int u = root,v;for(int i = 29;i>=0;i--){v = (va&(1<<i))?1:0;if(Next[u][v]==-1)Next[u][v]=newnode();u = Next[u][v];val[u]++;}}void Delete(int va){int u = root,v;for(int i = 29;i>=0;i--){v = (va&(1<<i))?1:0;u = Next[u][v];val[u]--;}}int query(int x){int u = root,v;for(int i = 29;i>=0;i--){v = (x&(1<<i))?1:0;if(v==1){if(Next[u][0]!=-1 && val[Next[u][0]])u = Next[u][0];else{u = Next[u][1];x^=(1<<i);}}else{if(Next[u][1]!=-1 && val[Next[u][1]]){u = Next[u][1];x^=(1<<i);}else u = Next[u][0];}}return x;}}T;int main(){     int q; T.init(); T.insert(0); scanf("%d",&q); while(q--) {         string op; int v; cin >> op >> v; if(op=="+")     T.insert(v); if(op=="-") T.Delete(v); if(op=="?") printf("%d\n",T.query(v)); }}

D. Vasiliy's Multiset

time limit per test

4 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

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.

Input

The first line of the input contains a single integer q (1 ≤ q ≤ 200 000) — the number of queries Vasiliy has to perform.

Each of the following q lines of the input contains one of three characters '+', '-' or '?' and an integer xi (1 ≤ xi ≤ 109). It's guaranteed that there is at least one query of the third type.

Note, that the integer 0 will always be present in the set A.

Output

For each query of the type '?' print one integer — the maximum value of bitwise exclusive OR (XOR) of integer xi and some integer from the multiset A.

Example

input

10+ 8+ 9+ 11+ 6+ 1? 3- 8? 3? 8? 11

output

11101413

Note

After first five operations multiset A contains integers 0, 8, 9, 11, 6 and 1.

The answer for the sixth query is integer  — maximum among integers , , ,  and .