Submission #1032812

#	Time	Username	Problem	Language	Result	Execution time	Memory
1032812		vjudge1	Duathlon (APIO18_duathlon)	C++17	100 / 100	94 ms	30116 KiB

count_triplets

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

#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
 
template <typename T> using oset = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

#define vt vector
#define rep(i, a, b) for(int i = a; i < (b); ++i)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define pb push_back

typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vi;

template<class T> bool chmin(T& a, const T& b) {
	return b<a?a=b, 1:0;
}
template<class T> bool chmax(T& a, const T& b) { 
	return a<b?a=b, 1:0;
} 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
mt19937_64 rng_64(chrono::steady_clock::now().time_since_epoch().count());

int main() {
	cin.tie(0)->sync_with_stdio(0);
	cin.exceptions(cin.failbit);
	int n, m;
	cin >> n >> m;
	vt<vt<int>> g(n+1);
	rep(i, 0, m) {
		int u, v;
		cin >> u >> v;
		g[u].pb(v);
		g[v].pb(u);
	}
	int nc=n;
	vt<int> stk;
	vt<int> low(n+1), id(n+1);
	vt<vt<int>> adj(n+m+1);
	int tim=0;
	auto dfs = [&](int at, int par, auto &&dfs) -> void {
		id[at]=low[at]=++tim;
		stk.pb(at);
		for(int to:g[at]) {
			if(to == par)continue;
			if(!id[to]) {
				dfs(to, at, dfs);
				chmin(low[at], low[to]);
				if(low[to] >= id[at]) {
					nc++;
					adj[nc].pb(at);
					adj[at].pb(nc);
//					cout << at << " ";
					while(1) {
						int tmp = stk.back();
						adj[tmp].pb(nc);
						adj[nc].pb(tmp);
//						cout << tmp << " ";
						stk.pop_back();
						if(tmp==to)break;
					}
//					cout << endl;
				}
			}
			else low[at] = min(low[at], id[to]);
		}
	};
	for(int i = 1;i<=n;i++) {
		if(!id[i])
			dfs(i, i, dfs);
	}
	vt<int> dp(n+m+1);
	ll ans=0;
	vt<bool> vis(n+m+1);
	auto dfs2  = [&](int at, int par, auto &&dfs2) -> void {
		if(at <= n)dp[at]=1;
		vis[at]=1;
		for(int to:adj[at]) {
			if(to==par)continue;
			dfs2(to, at, dfs2);
			dp[at]+=dp[to];
		}
	};
	int sss;
	auto dfs3  = [&](int at, int par, auto &&dfs3) -> void {
		if(at <= n) {
			ll sum=sss-dp[at];
			for(int to:adj[at]) {
				if(to==par)continue;
				dfs3(to, at, dfs3);
				ans+=2ll*dp[to]*sum;
				sum+=dp[to];
			}
		}
		else {
			ll sum=sss-dp[at];
			ll cnt2=0;
			for(int to:adj[at]) {
				if(to==par)continue;
				dfs3(to, at, dfs3);
				cnt2+=2ll*dp[to]*sum;
				sum+=dp[to];
			}
			ans+=cnt2*(sz(adj[at])-2);
		}
	};
	rep(i, 1, n+1) {
		if(!vis[i]) {
			dfs2(i, i, dfs2);
			sss=dp[i];
			dfs3(i, i, dfs3);
		}
	}
	cout << ans << "\n";	

}

• 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