Submission #969444

#	Time	Username	Problem	Language	Result	Execution time	Memory
969444		c2zi6	Duathlon (APIO18_duathlon)	C++14	100 / 100	75 ms	28504 KiB

count_triplets

#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define ff first
#define ss second
#define pb push_back
#define all(a) (a).begin(), (a).end()
#define replr(i, a, b) for (int i = int(a); i <= int(b); ++i)
#define reprl(i, a, b) for (int i = int(a); i >= int(b); --i)
#define rep(i, n) for (int i = 0; i < int(n); ++i)
#define mkp(a, b) make_pair(a, b)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> PII;
typedef vector<int> VI;
typedef vector<PII> VPI;
typedef vector<VI> VVI;
typedef vector<VVI> VVVI;
typedef vector<VPI> VVPI;
typedef pair<ll, ll> PLL;
typedef vector<ll> VL;
typedef vector<PLL> VPL;
typedef vector<VL> VVL;
typedef vector<VVL> VVVL;
typedef vector<VPL> VVPL;
template<class T> T setmax(T& a, T b) {if (a < b) return a = b; return a;}
template<class T> T setmin(T& a, T b) {if (a < b) return a; return a = b;}
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
template<class T>
using indset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

int n, m;
int bcc;
VVI initgp, bccgp;

VI vis, low, num;
int tc;
stack<int> st;

void tarjan(int u, int p = -1) {
	st.push(u);
	vis[u] = 1;
	low[u] = num[u] = tc++;
	for (int v : initgp[u]) if (v != p) {
		if (vis[v] == 1) {
			setmin(low[u], num[v]);
		} else if (vis[v] == 0) {
			tarjan(v, u);
			setmin(low[u], low[v]);
			if (low[v] >= num[u]) {
				bccgp[u].pb(n+bcc);
				while (st.top() != v) {
					bccgp[n+bcc].pb(st.top());
					st.pop();
				}
				bccgp[n+bcc].pb(st.top());
				st.pop();
				bcc++;
			}
		}
	}
	vis[u] = 2;
}

ll ans;
VI sub;
void dfs(int u, int p = -1) {
	sub[u] = (u < n);
	for (int v : bccgp[u]) if (v != p) {
		dfs(v);
		sub[u] += sub[v];
		if (u >= n) ans -= 1ll * bccgp[u].size() * sub[v] * (sub[v]-1);
	}
	if (u >= n) ans -= 1ll * bccgp[u].size() * (tc-sub[u]) * (tc-sub[u]-1);
}

void solve() {
	cin >> n >> m;
	initgp = VVI(n);
	bccgp = VVI(2*n);
	rep(i, m) {
		int u, v;
		cin >> u >> v;
		u--, v--;
		initgp[u].pb(v);
		initgp[v].pb(u);
	}
	vis = low = num = VI(n);
	sub = VI(2*n);
	bcc = 0;
	ans = 0;
	rep(u, n) if (!vis[u]) {
		tc = 0;
		tarjan(u);
		ans += 1ll * tc * (tc-1) * (tc-2);
		dfs(u);
	}
	cout << ans << endl;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);
    int t = 1;
    // cin >> t;
    while (t--) solve();
}

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