别喷我，燃尽了，90分。

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

const int BITS = 24;  // 2^24 > 10^7

struct Node {
    int son[2];
    int max_id;
    Node() {
        son[0] = son[1] = 0;
        max_id = -1;
    }
};

vector<Node> tr;
vector<int> root;
vector<int> s;
int n, m;

int new_node() {
    tr.push_back(Node());
    return tr.size() - 1;
}

// 非递归插入，避免递归爆栈
void insert(int idx, int k, int p, int q) {
    int cur_p = p, cur_q = q;
    vector<int> path;
    path.push_back(q);
    
    for (int i = k; i >= 0; i--) {
        int v = (s[idx] >> i) & 1;
        // 复制另一个分支
        tr[cur_q].son[v ^ 1] = tr[cur_p].son[v ^ 1];
        // 创建新分支节点
        tr[cur_q].son[v] = new_node();
        // 记录路径
        path.push_back(tr[cur_q].son[v]);
        // 移动到下一层
        cur_p = tr[cur_p].son[v];
        cur_q = tr[cur_q].son[v];
    }
    // 设置叶子节点的max_id
    tr[cur_q].max_id = idx;
    // 回溯更新路径上节点的max_id
    for (int i = path.size() - 2; i >= 0; i--) {
        int node = path[i];
        int left = tr[node].son[0];
        int right = tr[node].son[1];
        int max_left = (left == 0) ? -1 : tr[left].max_id;
        int max_right = (right == 0) ? -1 : tr[right].max_id;
        tr[node].max_id = max(max_left, max_right);
    }
}

int query(int root_idx, int C, int L) {
    int p = root_idx;
    for (int i = BITS - 1; i >= 0; i--) {
        int v = (C >> i) & 1;
        int best = tr[p].son[v ^ 1];
        if (best != 0 && tr[best].max_id >= L) {
            p = best;
        } else {
            p = tr[p].son[v];
            if (p == 0) break;  // 防止访问空节点
        }
    }
    return C ^ s[tr[p].max_id];
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    cin >> n >> m;
    s.resize(n + m + 5);
    root.resize(n + m + 5);
    
    for (int i = 1; i <= n; i++) {
        cin >> s[i];
        s[i] ^= s[i - 1];
    }
    
    // 初始化Trie
    tr.reserve((n + m) * 25 + 5);  // 预分配空间
    new_node();  // 创建0号空节点
    root[0] = new_node();
    insert(0, BITS - 1, 0, root[0]);
    
    for (int i = 1; i <= n; i++) {
        root[i] = new_node();
        insert(i, BITS - 1, root[i - 1], root[i]);
    }
    
    char op;
    int l, r, x;
    int now = n;
    
    for (int i = 0; i < m; i++) {
        cin >> op;
        if (op == 'A') {
            cin >> x;
            now++;
            s[now] = s[now - 1] ^ x;
            root[now] = new_node();
            insert(now, BITS - 1, root[now - 1], root[now]);
        } else {
            cin >> l >> r >> x;
            int C = s[now] ^ x;
            cout << query(root[r - 1], C, l - 1) << "\n";
        }
    }
    
    return 0;
}