Language: C++

#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <random>
#include <chrono>
#include <tuple>
#include <random>

using namespace std;

typedef long long ll;
typedef long double ld;
#define fastInp cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);

const ll SIZE = 1e6, INF = 1e9 * 1e9 + 10, MOD = 1e9 + 7;
ll n;
vector<ll> vec;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

void input() {
    cin >> n;
    vec.resize(n);

    for (int i = 0; i < n; i++) cin >> vec[i];
}

ll brute() {
    ll pw = (1ll << (n - 1));
    ll ans = 0;
    for (int i = 0; i < pw; i++) {
        set<ll> xs;
        ll curX = 0;
        for (int j = 0; j < n; j++) {
            curX ^= vec[j];
            if (j == n - 1 || ((1ll << j) & i)) {
                xs.insert(curX);
                curX = 0;
            }
        }
        ans += (xs.size() == 1);
    }

    return ans;
}

ll bpow(ll vl, ll pw, ll md = MOD) {
    if (pw == 0) {
        return 1;
    } else if (pw % 2 == 1) {
        ll a = bpow(vl, pw - 1, md);
        return (a * vl) % MOD;
    } else {
        ll b = bpow(vl, pw / 2, md);
        return (b * b) % MOD;
    }
}

ll sol() {
    ll x = 0, mx = 0;
    for (int i = 0; i < n; i++) {
        x ^= vec[i];
        mx = max(mx, vec[i]);
    }

    if (x == 0) {
        ll curInd = 0, pr = -1;
        vector<vector<ll>> cnt;
        cnt.resize(mx * 2 + 2);

        ll curX = 0;
        vector<pair<ll, ll>> bls;
        for (int i = 0; i < n; i++) {
            curX ^= vec[i];
            if (curX == 0) {
                bls.push_back({pr + 1, i});
                pr = i;
            }
        }

        ll i = 0;
        for (auto cur : bls) {
            ll curX = 0;
            for (int j = cur.first; j <= cur.second; j++) {
                curX ^= vec[j];
                cnt[curX].push_back(i);
            }
            i++;
        }

        ll ans = 0;
        for (int i = 0; i < cnt.size(); i++) {
            if (cnt[i].size() == 0) {
                continue;
            }
            pair<ll, ll> brd = {INF, -INF};
            for (auto cur : cnt[i]) {
                brd.first = min(brd.first, cur);
                brd.second = min(brd.second, cur);
            }

            ll curn = (brd.second - brd.first + 1);
            ll add = 0, l = 0;
            sort(cnt[i].begin(), cnt[i].end());
            for (int j = cnt[i].size() - 2; j >= 0; j--) {
                l += abs(cnt[i][j] - cnt[i][j + 1]);
                add += l;
            }
            ans += (bpow(2, cnt[i].size()) - 1 + MOD + l) % MOD;
            ans %= MOD;
        }

        return ans;
    } else {
        ll curX = 0, cnt = 0, cnt2 = 0;
        vector<ll> vals;
        for (int i = 0; i < n; i++) {
            curX ^= vec[i];
            if (curX == 0) {
                cnt2++;
                vals.push_back(0);
            }
            else if (curX == x) {
                cnt++;
                vals.push_back(1);
                curX = 0;
            }
        }

        ll dp[2];
        dp[0] = 1;
        dp[1] = 0;
        ll pr = 0;
        for (auto cur : vals) {
            ll pr1 = dp[0], pr2 = dp[1];
            if (cur == 0) {
                dp[0] = pr1 + pr2;
            } else {
                dp[1] = pr2 + pr1;
                dp[0] = pr2;
                pr = 0;
            }
            dp[0] %= MOD;
            dp[1] %= MOD;
        }

        return dp[1];
    }
}

int main() 
{
    fastInp;

    
    //input();
    input();
    cout << solve();
    return 0;
    ll t = 100;
    while (t--) {
        n = rng() % 10 + 1;
        vec.clear();
        ll x = 0, snd = rng() % 10 + 1;
        for (int i = 0; i < n; i++) {
            if (rng() % 2) {
                vec.push_back(snd);
            } else {
                vec.push_back(0);
            }

            x ^= vec[i];
        }

        if (1) {
            if (brute() != sol()) {
                cout << brute() << " " << sol() << " " << t << "\n";
                cout << n << " " << x << "\n";
                for (auto cur : vec) cout << cur << " ";
                cout << "\n";
                return 0;
            }
        }
    }

    cout << "ok"; // DONT FORGET MOD
    return 0;
}

// 192 / 216 - 8 / 9
// 192 / 8

// 54 / 72 - 3 / 4
// 54 / 6



Compiler output:
a.cc: In function 'int main()':
a.cc:162:13: error: 'solve' was not declared in this scope; did you mean 'sol'?
  162 |     cout << solve();
      |             ^~~~~
      |             sol