Submission #709613

#	Time	Username	Problem	Language	Result	Execution time	Memory
709613		GusterGoose27	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	100 / 100	511 ms	58844 KiB

joitter2

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;

const int MAXN = 1e5;
const int MAXM = 3e5;
vector<int> contained[MAXN];
vector<int> out_edges[MAXN];
vector<int> in_edges[MAXN];
int uf[MAXN];
set<int> inc[MAXN]; // specific nodes
set<int> out[MAXN]; // this is just general ccs
ll ans = 0;
int n, m;

void undo(int i) {
	ans -= (ll)contained[i].size()*inc[i].size();
	ans -= (ll)contained[i].size()*((int)contained[i].size()-1);
}

void make(int i) {
	ans += (ll)contained[i].size()*inc[i].size();
	ans += (ll)contained[i].size()*((int)contained[i].size()-1);
}

void merge(int a, int b) {
	a = uf[a];
	b = uf[b];
	if (a == b) return;
	if (contained[a].size() < contained[b].size()) swap(a, b);
	undo(a);
	undo(b);
	out[a].erase(b);
	out[b].erase(a);
	for (int v: contained[b]) {
		inc[a].erase(v);
		uf[v] = a;
		contained[a].push_back(v);
	}
	for (int w: inc[b]) {
		if (uf[w] != a) {
			inc[a].insert(w);
			out[uf[w]].insert(a);
			out[uf[w]].erase(b);
		}
	}
	for (int w: out[b]) {
		out[a].insert(w);
	}
	make(a);
	vector<int> ex;
	for (int v: inc[b]) {
		if (out[a].find(uf[v]) != out[a].end()) ex.push_back(v);
	}
	for (int v: out[b]) {
		if (out[v].find(a) != out[v].end()) ex.push_back(v);
	}
	out[b].clear();
	inc[b].clear();
	contained[b].clear();
	for (int v: ex) merge(v, a);
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(NULL);
	cin >> n >> m;
	iota(uf, uf+n, 0);
	for (int i = 0; i < n; i++) contained[i].push_back(i);
	for (int i = 0; i < m; i++) {
		int x, y; cin >> x >> y;
		x--; y--;
		if (uf[x] != uf[y]) {
			if (out[uf[y]].find(uf[x]) != out[uf[y]].end()) {
				merge(x, y);
			}
			else {
				undo(uf[y]);
				inc[uf[y]].insert(x);
				make(uf[y]);
				out[uf[x]].insert(uf[y]);
			}
		}
		cout << ans << "\n";
	}
}

• Subtask 1: 1 / 1
• Subtask 2: 16 / 16
• Subtask 3: 83 / 83