제출 #381099

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
381099		Return_0	철인 이종 경기 (APIO18_duathlon)	C++17	31 / 100	147 ms	26728 KiB

count_triplets

#pragma GCC optimize("Ofast,unroll-loops")
// #pragma comment(linker, "/stack:200000000")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,fma,tune=native")

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

typedef int ll;
typedef long double ld;
typedef pair <ll, ll> pll;

#ifdef SINA
#define dbg(...) __f(#__VA_ARGS__, __VA_ARGS__)
template <typename Arg1> void __f(const char* name, Arg1&& arg1) { cout << name << " : " << arg1 << std::endl; }
template <typename Arg1, typename... Args> void __f (const char* names, Arg1&& arg1, Args&&... args) {
	const char* comma = strchr(names + 1, ',');cout.write(names, comma - names) << " : " << arg1<<" | ";__f(comma+1, args...); }
#define dbg2(x, j, n) cout<< #x << " : "; output((j), (n), x, 1); cout.flush();
#else
#define dbg(...) 0
#define dbg2(x, j, n) 0
#endif
#define SZ(x) ((ll)((x).size()))
#define File(s, t) freopen(s ".txt", "r", stdin); freopen(t ".txt", "w", stdout);
#define input(j, n, a) for (int _i = (j); _i < (n)+(j); _i++) cin>> a[_i];
#define output(j, n, a, t) for (int _i = (j); _i < (n)+(j); _i++) cout<< a[_i] << (((t) && _i != (n)+(j)-1)? ' ' : '\n');
#define kill(x) return cout<< (x) << endl, 0
#define cl const ll
#define fr first
#define sc second
#define lc (v << 1)
#define rc (lc | 1)
#define mid ((l + r) >> 1)
#define All(x) (x).begin(), (x).end()

cl inf = sizeof(ll) == 4 ? (1e9 + 10) : (3e18), mod = 1e9 + 7, MOD = 998244353;

template <class A,class B> ostream& operator << (ostream& out,const pair<A,B>&a){return out<<'('<<a.first<<", "<<a.second<<')';}
template <class A> ostream& operator << (ostream& out, const vector<A> &a) {
	out<< '['; for (int i = -1; ++i < int(a.size());) out<< a[i] << (i + 1 < int(a.size()) ? ", " : ""); return out<<']'; }
template <class T, typename _t = less <T> > using Tree = tree <T, null_type, _t, rb_tree_tag, tree_order_statistics_node_update>;

cl N = 1e5 + 7, M = 2e5 + 7;

ll h [N], sz [M], n, m, _n;
vector <ll> adj [N], adj2 [M], stk;
long long ans;

ll preDFS (ll v, ll pr) {
	_n++;
	ll low = h[v] = h[pr] + 1;
	stk.push_back(v);
	for (auto &u : adj[v]) {
		if (h[u]) low = min(low, h[u]);
		else low = min(low, preDFS(u, v));
	}
	if (low == h[pr]) {
		adj2[pr].push_back(n + v);
		for (; stk.back() != pr; stk.pop_back()) adj2[v + n].push_back(stk.back());
	}
	return low;
}

void dfs (ll v, ll pr) {
	sz[v] = v <= n;
	for (auto &u : adj2[v]) {
		dfs(u, v);
		sz[v] += sz[u];
		if (v > n) ans -= 1LL * (SZ(adj2[v]) - (pr == 0)) * sz[u] * (sz[u] - 1);
	}
	if (v > n) ans -= 1LL * SZ(adj2[v]) * (_n - sz[v]) * (_n - sz[v] - 1);
}

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

	cin>> n >> m;
	for (ll i = 0, v, u; i < m; i++) {
		cin>> v >> u;
		adj[v].push_back(u);
		adj[u].push_back(v);
	}

	stk.push_back(0);
	for (ll i = 1; i <= n; i++) if (!h[i]) {
		_n = 0;
		preDFS(i, 0);
		ans += 1LL * _n * (_n - 1) * (_n - 2);
		dfs(i, 0);
	}

	cout<< ans << '\n';

	cerr<< "\nTime elapsed: " << 1000 * clock() / CLOCKS_PER_SEC << "ms\n";

	return 0;
}
/*
4 3
1 2
2 3
3 4

4 4
1 2
2 3
3 4
2 4

*/

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