Submission #1500716

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

using pii = pair<int, int>;
using ll = long long;

void dfs(int v, int prev, int now, vector<vector<pii>> const& T, map<int, ll>& m) {
    m[now] += 1;
    for(auto& p : T[v]) {
        int to = p.first, cost = p.second;
        if(to == prev) {
            continue;
        }
        dfs(to, v, now ^ cost, T, m);
    }
}

int main() {
    int N, X;
    cin >> N >> X;
    vector<vector<pii>> T(N);
    for(int i = 0; i < N - 1; ++i) {
        int x, y, c;
        cin >> x >> y >> c;
        x--; y--;
        T[x].emplace_back(y, c);
        T[y].emplace_back(x, c);
    }

    map<int, ll> m;
    dfs(0, -1, 0, T, m);
    ll res = 0;
    for(auto& p : m) {
        int x = p.first ^ X;
        if(x == p.first) {
            res += p.second * (p.second - 1);
        } else if(m.count(x) == 1) {
            res += p.second * m[x];
        }
    }
    res /= 2;
    cout << res << endl;
}

Submission Info

Judge Result