Submission #297275

#	Time	Username	Problem	Language	Result	Execution time	Memory
297275		srvlt	Duathlon (APIO18_duathlon)	C++14	25 / 100	95 ms	632 KiB

count_triplets

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define pb push_back
#define all(x) begin(x), end(x)
#define SZ(x) (int)(x).size()
#define cps(x) sort(all(x)), (x).erase(unique(all(x)), end(x))
#define cps2(x, y) sort(all(x), y), (x).erase(unique(all(x)), end(x))
#define mem(x, y) memset(& x, y, sizeof(x))
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int n0 = 1003;
int n, m, root, used[n0], sz[n0];
int up[n0], in[n0], T, last[n0];
vector <int> g[n0];
ll cur;

void dfs(int v, int p) {
	used[v] = 1, sz[v] = 1, in[v] = ++T;
	up[v] = in[v];
	int ok = 0;
	vector <int> child;
	child.clear();
	for (int to : g[v]) {
		if (to == p) continue;
		if (used[to] == 1 && in[to] < in[v])
			up[v] = min(up[v], in[to]);
		if (!used[to]) {
			dfs(to, v);
			sz[v] += sz[to];
			up[v] = min(up[v], up[to]);
			if (up[to] == 1) ok = 1;
			child.pb(to);
		}
	}
	if (up[v] == 1) last[v] = v;
	else if (v != root) last[v] = last[p];
	if (ok) last[v] = v;
	if (v != root) {
		ll bad = 1;
		for (int to : child) {
			if (!last[v] || up[to] >= in[last[v]]) {
				cur += bad * sz[to];
				bad += sz[to];
			}
		}
	}
	used[v] = 2;
}

ll comp;
void go(int v) {
	used[v] = 1, comp++;
	for (int to : g[v])
		if (!used[to]) go(to);
}

int main() {
	ios_base::sync_with_stdio(false), cin.tie(NULL);
	cin >> n >> m;
	for (int i = 0; i < m; i++) {
		int x, y;
		cin >> x >> y;
		g[x].pb(y), g[y].pb(x);
	}
	ll res = 0;
	for (int i = 1; i <= n; i++) {
		if (!used[i]) {
			comp = 0;
			go(i);
			res += comp * (comp - 1) * (comp - 2);
		}
	}
	for (int i = 1; i <= n; i++) {
		root = i, cur = 0, T = 0;
		mem(used, 0), mem(last, 0);
		dfs(i, i);
		cur *= 2;
		res -= cur;
	}
	cout << res;
}

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