Submission #939314

#	Time	Username	Problem	Language	Result	Execution time	Memory
939314		WonderfulWhale	Making Friends on Joitter is Fun (JOI20_joitter2)	C++17	0 / 100	2 ms	6744 KiB

joitter2

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

#define int int64_t
#define pb push_back
#define pii pair<int, int>
#define st first
#define nd second
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()

const int MAXN = 100'009;

int cnt[MAXN];
int p[MAXN];
int sz[MAXN];
set<int> M[MAXN];
set<pii> S;
int ans;

int Find(int x) {
	return x==p[x]?x:p[x]=Find(p[x]);
}

void Union(int a, int b) {
	int A = Find(a), B = Find(b);
	if(sz(M[A])<sz(M[B])) swap(A, B);
	ans -= sz[A]*(sz[A]-1);
	ans -= sz[B]*(sz[B]-1);
	ans -= sz[A]*sz(M[A]);
	ans -= sz[B]*sz(M[B]);
	//cerr << "after deleting: " << ans << "\n";
	sz[A] += sz[B];
	p[B] = A;
	for(int x:M[B]) {
		M[A].insert(x);
	}
	M[B].clear();
	M[A].erase(a);
	M[A].erase(b);
	ans += sz[A]*(sz[A]-1);
	ans += sz[A]*sz(M[A]);
	//cerr << "new stats: " << sz[A] << " " << sz(M[A]) << "\n";
}

int32_t main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

	int n, m;
	cin >> n >> m;
	iota(p, p+n+1, 0);
		fill(sz, sz+n+1, 1);
	for(int i=0;i<m;i++) {
		int a, b;
		cin >> a >> b;
		if(S.count({b, a})==0) {
			//cerr << "adding\n";
			int B = Find(b);
			ans -= sz(M[B])*sz[B];
			M[B].insert(a);
			ans += sz(M[B])*sz[B];
		} else {
			//cerr << "Merging\n";
			Union(a, b);		
		}
		S.insert({a, b});
		cout << ans << "\n";
	}
}

• Subtask 1: 0 / 1
• Subtask 2: 0 / 16
• Subtask 3: 0 / 83