Submission #158198

#	Time	Username	Problem	Language	Result	Execution time	Memory
158198		maruii	Duathlon (APIO18_duathlon)	C++14	0 / 100	129 ms	18296 KiB

count_triplets

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

int N, M, dfn[100005], dfnn, low[100005], cpn[100005], cpnn, sz[100005];
vector<int> edge[100005], bdge[100005];
ll ans;

void dfs(int x, int p) {
	dfn[x] = low[x] = ++dfnn;
	for (auto i : edge[x]) {
		if (i == p) continue;
		if (dfn[i]) {
			if (dfn[i] < dfn[x]) low[x] = min(low[x], dfn[i]);
			continue;
		}
		dfs(i, x);
		low[x] = min(low[x], low[i]);
	}
}

void bcc(int x, int c) {
	cpn[x] = c;
	sz[c]++;
	for (auto i : edge[x]) {
		if (cpn[i]) continue;
		if (low[i] == dfn[i]) {
			bdge[++cpnn].push_back(c);
			bdge[c].push_back(cpnn);
			bcc(i, cpnn);
		}
		else bcc(i, c);
	}
}

void calc(int x, int p) {
	ll n = sz[x], t = (N - n) * (N - n);
	ans += n * (n - 1) * (n - 2) + 2 * (n - 1) * (n - 1) * (N - n);
	for (auto i : bdge[x]) {
		if (i == p) continue;
		calc(i, x);
		sz[x] += sz[i];
		t -= 1ll * sz[i] * sz[i];
	}
	ans += n * (t - 1ll * (N - sz[x]) * (N - sz[x]));
}

int main() {
	ios_base::sync_with_stdio(0), cin.tie(0);
	cin >> N >> M;
	for (int i = 0; i < M; ++i) {
		int x, y; cin >> x >> y;
		edge[x].push_back(y);
		edge[y].push_back(x);
	}
	dfs(1, 1);
	bcc(1, ++cpnn);
	calc(1, 1);
	cout << ans;
	return 0;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10