Submission #1111176

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> P;

vector< vector<P> > g;
vector<int> rc;

void dfs(int cur, int par, int cost) {
	rc[cur] = cost;
	for (P nex : g[cur]) {
		if (nex.first == par) continue;
		dfs(nex.first, cur, cost ^ nex.second);
	}
}

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int n, x;
	cin >> n >> x;
	g.resize(n);
	for (int i = 0; i < n - 1; i++) {
		int x, y, c;
		cin >> x >> y >> c;
		x--;
		y--;
		g[x].emplace_back(y, c);
		g[y].emplace_back(x, c);
	}

	rc.resize(n, -1);
	dfs(0, -1, 0);

	ll ans = 0;
	map<int, int> cnt;
	for (int i = 0; i < n; i++) {
		int tar = rc[i] ^ x;
		if (cnt.find(tar) != cnt.end()) {
			ans += cnt[tar];
		}
		cnt[rc[i]]++;
	}
	cout << ans << endl;
	return 0;
}

Submission Info

Judge Result