a.cpp

#include <bits/stdc++.h>
#define f first
#define s second
#define ll long long
#define pb push_back
#define IOS ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)
#define mk make_pair
using namespace std;

const int MAXN = 1e6 + 5;
const int INF = 1e9 + 7;
const int MOD = 1e9 + 7;

struct trie{
    int links[2];
    int cnt = 0;
    bool leaf = 0;
} t[MAXN];
int vertex = 0;

void add(ll mask){
    int v = 0;
    t[v].cnt++;
    for (int i = 40; i >= 0; i--){
        int bit = (mask >> i) & 1;
        if (t[v].links[bit] == -1){
            vertex++;
            t[v].links[bit] = vertex;
            t[vertex].links[0] = -1;
            t[vertex].links[1] = -1;
        }
        v = t[v].links[bit];
        t[v].cnt++;
    }
}

void del(ll mask){
    int v = 0;
    t[v].cnt--;
    for (int i = 40; i >= 0; i--){
        int bit = (mask >> i) & 1;
        v = t[v].links[bit];
        t[v].cnt--;
    }
}

ll ffind(ll mask){
    int v = 0;
    ll xxor = 0;
    for (int i = 40; i >= 0; i--){
        int bit = (mask >> i) & 1;
        if (t[v].links[1 ^ bit] != -1 && t[t[v].links[1 ^ bit]].cnt > 0){
            v = t[v].links[1 ^ bit];
            xxor ^= (1LL << i);
        }
        else{
            v = t[v].links[bit];
        }
    }
    return xxor;
}

void solve(int Test){
    for (int i = 0; i < 26; i++){
        t[0].links[i] = -1;
    }
    int n;
    cin >> n;
    a[0] = 0;
    for (int i = 1; i <= n; i++){
        cin >> a[i];
    }
    suf[n + 1] = 0;
    add(0);
    add(0);
    suf[0] = 0;
    for (int i = n; i >= 1; i--){
        suf[i] = suf[i + 1] ^ a[i];
        add(suf[i]);
    }
    ll pref = 0;
    ll ans = 0;
    for (int i = 0; i <= n; i++){
        pref ^= a[i];
        del(suf[i]);

        ll best_xor = ffind(pref);
        ans = max(ans, best_xor);
    }

    cout << ans << "\n";
}

main() {
    IOS;
    srand(time(0));
    int t = 1;
    cin >> t;
    int T = 1;
    while(t--){
        solve(T);
        T++;
    }
}