Source Code
#include <bits/stdc++.h>

using namespace std;

#define cin_2d(vec, n, m) for(int i = 0; i < n; i++) for(int j = 0; j < m && cin >> vec[i][j]; j++);
#define cout_2d(vec, n, m) for(int i = 0; i < n; i++, cout << "\n") for(int j = 0; j < m && cout << vec[i][j] << " "; j++);
#define cout_map(mp) for(auto& [f, s] : mp) cout << f << "  " << s << "\n";
#define Time cerr << "Time Taken: " << (float)clock() / CLOCKS_PER_SEC << " Secs" << "\n";
#define fixed(n) fixed << setprecision(n)
#define ceil(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
#define fill(vec, value) memset(vec, value, sizeof(vec));
#define Num_of_Digits(n) ((int)log10(n) + 1)
#define mod_combine(a, b, m) (((a % m) * (b % m)) % m)
#define all(vec) vec.begin(), vec.end()
#define rall(vec) vec.rbegin(), vec.rend()
#define sz(x) int(x.size())
#define debug(x) cout << #x << ": " << (x) << "\n";
#define fi first
#define se second
#define Pair pair < int, int >
#define ll long long
#define ull unsigned long long
#define Mod  1'000'000'007
#define OO 2'000'000'000
#define EPS 1e-9
#define PI acos(-1)

template < typename T = int > istream& operator >> (istream &in, vector < T > &v) {
    for (auto &x: v) in >> x;
    return in;
}

template < typename T = int > ostream& operator << (ostream &out, const vector < T > &v) { 
    for (const T &x: v) out << x << ' '; 
    return out;
}

void AhMeD_HoSSaM(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout); 
    #endif
}

vector < vector < vector < Pair > > > tree(2, vector < vector < Pair > > (1e5 + 5));
vector < int > Sz(1e5 + 10, 1);
int bits[2][30][100'005];

void add_edge(int u, int v, int w, int t){
    tree[t][u].push_back({v, w}), tree[t][v].push_back({u, w});
}

void dfs(int u, int p, int t){
    for(auto& [v, w] : tree[t][u]){
        if(v == p) continue;
        dfs(v, u, t);
        Sz[u] += Sz[v];
        for(int b = 0; b < 30; b++){
            if(w & (1 << b))
                bits[t][b][u] += Sz[v] - bits[t][b][v];
            else
                bits[t][b][u] += bits[t][b][v];
        }
    }
}

void dfs2(int u, int p, int t){
    for(auto& [v, w] : tree[t][u]){
        if(v == p) continue;
        for(int b = 0; b < 30; b++){
            int last_p = 0;
            if(w & (1 << b))
                last_p = Sz[v] - bits[t][b][v];
            else
                last_p = bits[t][b][v];
            if(w & (1 << b))
                bits[t][b][v] += (Sz[u] - Sz[v]) - (bits[t][b][u] - last_p);
            else
                bits[t][b][v] += bits[t][b][u] - last_p;
        }
        Sz[v] += Sz[u] - Sz[v];
        dfs2(v, u, t);
    }
}

void Solve(){
    int n;
    cin >> n;
    fill(bits, 0);
    for(int i = 0, u, v, w; i < n - 1 && cin >> u >> v >> w; i++) add_edge(u, v, w, 0);
    for(int i = 0, u, v, w; i < n - 1 && cin >> u >> v >> w; i++) add_edge(u, v, w, 1);
    dfs(1, 0, 0);
    dfs2(1, 0, 0);
    Sz.assign(1e5 + 10, 1);
    dfs(1, 0, 1);
    dfs2(1, 0, 1);
    ll ans = 0;
    for(int b = 0; b < 30; b++){
        for(int u = 1; u <= n; u++){
            ans += ((1 << b) % Mod * (bits[0][b][u] * (n - bits[1][b][u])) % Mod) % Mod;
            ans %= Mod;
            ans += ((1 << b) % Mod * (bits[1][b][u] * (n - bits[0][b][u])) % Mod) % Mod;
            ans %= Mod;
        }
    }
    cout << ans << '\n';
}

int main(){
    AhMeD_HoSSaM();
    int t = 1;
    //cin >> t;
    while(t--)
        Solve();
    return 0;
}
Copy
Trees xOr 7oSkaa
GNU G++17
33 ms
28.9 MB
Wrong Answer