Submission #379412

#	Time	Username	Problem	Language	Result	Execution time	Memory
379412		Return_0	Pipes (CEOI15_pipes)	C++17	20 / 100	1114 ms	23404 KiB

pipes

#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 < ll(a.size());) out<< a[i] << (i + 1 < ll(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>;

struct bridge_online {
	vector <ll> par, dsu_2ecc, dsu_cc, dsu_cc_size;
	ll bridges, lca_iteration;
	vector <ll> last_visit;

	void init(ll n) {
		par.resize(n);
		dsu_2ecc.resize(n);
		dsu_cc.resize(n);
		dsu_cc_size.resize(n);
		lca_iteration = 0;
		last_visit.assign(n, 0);
		for (ll i = 0; i < n; ++i) {
			dsu_2ecc[i] = i;
			dsu_cc[i] = i;
			dsu_cc_size[i] = 1;
			par[i] = -1;
		}
		bridges = 0;
	}

	ll find_2ecc (ll v) {
		if (v == -1) return -1;
		return dsu_2ecc[v] == v ? v : dsu_2ecc[v] = find_2ecc(dsu_2ecc[v]);
	}

	ll find_cc(ll v) {
		v = find_2ecc(v);
		return dsu_cc[v] == v ? v : dsu_cc[v] = find_cc(dsu_cc[v]);
	}

	void make_root(ll v) {
		v = find_2ecc(v);
		ll root = v;
		ll child = -1;
		while (v != -1) {
			ll p = find_2ecc(par[v]);
			par[v] = child;
			dsu_cc[v] = root;
			child = v;
			v = p;
		}
		dsu_cc_size[root] = dsu_cc_size[child];
	}

	void merge_path (ll a, ll b) {
		++lca_iteration;
		vector<ll> path_a, path_b;
		ll lca = -1;
		while (lca == -1) {
			if (a != -1) {
				a = find_2ecc(a);
				path_a.push_back(a);
				if (last_visit[a] == lca_iteration){
					lca = a;
					break;
				}
				last_visit[a] = lca_iteration;
				a = par[a];
			}
			if (b != -1) {
				b = find_2ecc(b);
				path_b.push_back(b);
				if (last_visit[b] == lca_iteration){
					lca = b;
					break;
				}
				last_visit[b] = lca_iteration;
				b = par[b];
			}
		}

		for (ll v : path_a) {
			dsu_2ecc[v] = lca;
			if (v == lca) break;
			--bridges;
		}
		for (ll v : path_b) {
			dsu_2ecc[v] = lca;
			if (v == lca)
				break;
			--bridges;
		}
	}

	void add_edge(ll a, ll b) {
		a = find_2ecc(a);
		b = find_2ecc(b);
		if (a == b) return;

		ll ca = find_cc(a);
		ll cb = find_cc(b);

		if (ca != cb) {
			++bridges;
			if (dsu_cc_size[ca] > dsu_cc_size[cb]) {
				swap(a, b);
				swap(ca, cb);
			}
			make_root(a);
			par[a] = dsu_cc[a] = b;
			dsu_cc_size[cb] += dsu_cc_size[a];
		} else {
			merge_path(a, b);
		}
	}
} ds;

set <pll> st;

void In (ll v, ll u) {
	if (v > u) swap(v, u);
	if (!v) return;
	st.insert({v, u});
}

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

	ll n, m;
	cin>> n >> m;

	ds.init(n);
	for (ll i = 0, v, u; i < m; i++) {
		cin>> v >> u;
		ds.add_edge(--v, --u);
	}

	for (ll i = 0; i < n; i++) In(ds.find_2ecc(i) + 1, ds.par[ds.find_2ecc(i)] + 1);

	for (auto &x : st) cout<< x.fr << ' ' << x.sc << '\n';

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

	return 0;
}
/*
10 11
1 7
1 8
1 6
2 8
6 7
5 8
2 5
2 3
2 4
3 4
10 9

*/

• Subtask 1: 0 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 10
• Subtask 5: 10 / 10
• Subtask 6: 0 / 10
• Subtask 7: 10 / 10
• Subtask 8: 0 / 10
• Subtask 9: 0 / 10
• Subtask 10: 0 / 10