题意：给你一些数字，再询问Q个问题，每个问题给一个数字，使这个数字和之前给出的数字的异或和最大。

构造字典树，高位在前，低位在后

然后顺着字典树根向深处递归查询

#include<cstdio>
#include<cmath>
#include<cstring>
#include<queue>
#include<vector>
#include<map>
#include<set>
#include<string>
#include<iostream>
#include<functional>
#include<algorithm>

using namespace std;
typedef long long LL;
typedef pair<LL, int> PLI;

const int MX = 2e5 + 5;
const int INF = 0x3f3f3f3f;

struct Node {
    Node *Next[2];
    Node() {
        Next[0] = Next[1] = NULL;
    }
};

void trie_add(Node*root, int S) {
    Node *p = root;
    for(int i = 31; i >= 0; i--) {
        int id = ((S & (1 << i)) != 0);
        if(p->Next[id] == NULL) {
            p->Next[id] = new Node();
        }
        p = p->Next[id];
    }
}

int trie_query(Node*root, int S) {
    Node *p = root;
    int ans = 0;
    for(int i = 31; i >= 0; i--) {
        int id = ((S & (1 << i)) != 0);
        if(p->Next[id ^ 1] != NULL) {
            ans |= (id ^ 1) << i;
            p = p->Next[id ^ 1];
        } else {
            ans |= id << i;
            p = p->Next[id];
        }
    }
    return ans;
}

int main() {
    //freopen("input.txt", "r", stdin);
    int T, n, Q, t, ansk = 0;
    scanf("%d", &T);
    while(T--) {
        scanf("%d%d", &n, &Q);
        Node *root = new Node();

        for(int i = 1; i <= n; i++) {
            scanf("%d", &t);
            trie_add(root, t);
        }

        printf("Case #%d:\n", ++ansk);
        while(Q--) {
            scanf("%d", &t);
            printf("%d\n", trie_query(root, t));
        }
    }
    return 0;
}