Submission #720834

#	Time	Username	Problem	Language	Result	Execution time	Memory
720834		NothingXD	Duathlon (APIO18_duathlon)	C++17	31 / 100	153 ms	18952 KiB

count_triplets

/*

   Wei Wai Wei Wai
   Zumigat nan damu dimi kwayt rayt

*/

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

typedef long long ll;
typedef double ld;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef complex<ld> point;
/*typedef __uint128_t L;
  struct FastMod {
  ull b, m;
  FastMod(ull b) : b(b), m(ull((L(1) << 64) / b)) {}
  ull reduce(ull a) {
  ull q = (ull)((L(m) * a) >> 64);
  ull r = a - q * b; // can be proven that 0 <= r < 2*b
  return r >= b ? r - b : r;
  }
  };
  FastMod FM(2);
*/
void debug_out() { cerr << endl; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
	cerr << " " << H;
	debug_out(T...);
}

#define debug(...) cerr << "(" << #__VA_ARGS__ << "):", debug_out(__VA_ARGS__)
#define all(x) x.begin(), x.end()
#define MP(x, y) make_pair(x, y)
#define F first
#define S second

//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int maxn = 1e5 + 10;
const int inf = 1e9;

int n, m, par[maxn], a[maxn], cnt[maxn], sz[maxn], h[maxn];
vector<int> g[maxn], t[maxn];
bool vis[maxn], mark[maxn];
ll ans = 0;

int dfs(int v){
	vis[v] = true;
	int res = h[v], tmp = 0, cnt = (h[v] != 0);
	for (auto u: g[v]){
		if (!vis[u]){
			h[u] = h[v] + 1;
			int x = dfs(u);
			res = min(res, x);
			tmp = max(tmp, x);
			cnt++;
		}
		else res = min(res, h[u]);
	}
	if (cnt > 1 && tmp >= h[v]) mark[v] = true;
	return res;
}

int getpar(int v){
	return (par[v] == -1? v: par[v] = getpar(par[v]));
}

void merge(int u, int v){
	if ((u = getpar(u)) == (v = getpar(v))) return;
	par[v] = u;
}

void solve(int v, int p = -1){
	vis[v] = true;
	sz[v] = cnt[v];
	for (auto u: t[v]){
		if (u != p){
			solve(u, v);
			sz[v] += sz[u];
		}
	}
}

void Calc(int v, int r, int p = -1){
	ans += 1ll * (sz[r] - cnt[v]) * (sz[r] - cnt[v] - 1);
	if (mark[v]){
		for (auto u: g[v]){
			ans += 1ll * cnt[u] * (cnt[u] - 1);
			if (u != p) ans -= 1ll * sz[u] * (sz[u] - 1);
			else ans -= 1ll * (sz[r] - sz[v]) * (sz[r] - sz[v] - 1);
		}
	}
	else{
		ans += 1ll * cnt[v] * (cnt[v]-1) * (cnt[v]-2);
		for (auto u: g[v]){
			if (u != p){
				ans += 2ll * sz[u] * cnt[v] * (cnt[v]-1);
				ans -= 1ll * sz[u] * (sz[u] - 1);
			}
			else{
				ans += 2ll * (sz[r] - sz[v]) * cnt[v] * (cnt[v]-1);
				ans -= 1ll * (sz[r] - sz[v]) * (sz[r] - sz[v] - 1);
			}
		}
	}
	for (auto u: t[v]) if (u != p) Calc(u, r, v);
}


int main(){
	ios_base::sync_with_stdio(false); cin.tie(0);

	memset(par, -1, sizeof par);
	cin >> n >> m;
	for (int i = 1; i <= m; i++){
		int u, v; cin >> u >> v;
		g[u].push_back(v);
		g[v].push_back(u);
	}

	for (int i = 1; i <= n; i++) if (!vis[i]) dfs(i);
	for (int i = 1; i <= n; i++){
		for (auto u: g[i]){
			if (u > i && !mark[u] && !mark[i]) merge(i, u);
		}
	}

	for (int i = 1; i <= n; i++){
		a[i] = getpar(i);
		cnt[a[i]]++;
	}

	for (int i = 1; i <= n; i++){
		for (auto u: g[i]){
			if (u > i && (mark[u] || mark[i]) && getpar(u) != getpar(i)){
				t[a[u]].push_back(a[i]);
				t[a[i]].push_back(a[u]);
				merge(u, i);
			}
		}
	}

	memset(vis, false, sizeof vis);

	for (int i = 1; i <= n; i++){
		if (!vis[a[i]]){
			solve(a[i]);
			Calc(a[i], a[i]);
		}
	}

	cout << ans << '\n';

	return 0;
}

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