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

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 x_i (1 ≤ x_i ≤ 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 x_i 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 .

新技能get啊。

以前都不知道这种用字典树搞。

关于字典树的入门可以看这个   http://blog.csdn.net/say_c_box/article/details/52073513

查询操作就是，找到可以让该位为1的儿子节点，向下访问。因为越高位是1数就越大嘛。

最多不过30层，所以直接建30层的树即可。

有一句一定要注意：Note, that the integer 0 will always be present in the set A.

#include <cstdio>#include <cstring>#include <string>#include <iostream>#include <algorithm>#include <vector>#include <queue>#include <set>#include <map>#include <string>#include <cmath>#include <cstdlib>using namespace std;const int MAXN =100000+10;const long long INF =100000000000007;struct node{    node *next[2];    int cnt;    node(){        memset(next,NULL,sizeof(next));        cnt=0;    }};node *p,*root=new node();void _insert(int x){    p=root;    for(int i=30;i>=0;i--){        int num=x&(1<<i)?1:0;        if(p->next[num]==NULL)            p->next[num]=new node();        p=p->next[num];        p->cnt++;    }}void _delete(int x){    p=root;    for(int i=30;i>=0;i--){        int num=x&(1<<i)?1:0;        p=p->next[num];        p->cnt--;    }}int query(int x){    int res=0;    p=root;    for(int i=30;i>=0;i--){        int num=x&(1<<i)?0:1;        node *temp;        temp=p->next[num];        if(temp&&temp->cnt>0){            res+=pow(2.0,i);            p=temp;        }        else{            p=p->next[!num];        }    }    return res;}int main(){    int q;    _insert(0);    scanf("%d",&q);    getchar();    while(q--){        char op[2];        int x;        scanf("%s%d",op,&x);        if(op[0]=='+')            _insert(x);        else if(op[0]=='-')            _delete(x);        else            printf("%d\n",query(x));    }    return 0;}