Submission #211904

#	Time	Username	Problem	Language	Result	Execution time	Memory
211904		ryansee	Making Friends on Joitter is Fun (JOI20_joitter2)	C++14	100 / 100	1012 ms	94968 KiB

joitter2

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

#define FAST ios_base::sync_with_stdio(false); cin.tie(0);
#define pb push_back
#define eb emplace_back
#define ins insert
#define ph push
#define f first
#define s second
#define cbr cerr << "hi\n"
#define mmst(x, v) memset((x), v, sizeof ((x)))
#define siz(x) ll(x.size())
#define all(x) (x).begin(), (x).end()
#define lbd(x, y) lower_bound(all(x), y)
#define ubd(x, y) upper_bound(all(x), y)
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());    //can be used by calling rng() or shuffle(A, A+n, rng)
inline long long rand(long long x, long long y) { return (rng() % (y+1-x)) + x; } //inclusivesss
string inline to_string(char c) {string s(1,c);return s;} template<typename T> inline T gcd(T a,T b){ return a==0?llabs(b):gcd(b%a,a); }

typedef long long ll; 
typedef long double ld;
#define FOR(i,s,e) for(ll i=s;i<=ll(e);++i)
#define DEC(i,s,e) for(ll i=s;i>=ll(e);--i)
typedef pair<ll,ll>pi; typedef pair<ll,pi>spi; typedef pair<pi,pi>dpi;

#define LLINF ((long long)1e18)
#define INF int(1e9+1e6)
#define MAXN (300006)
ll n,m,ans,fake[MAXN],deg[MAXN]; // rmbr to pass down everything including fake and deg!!!!
struct ufds_ {
	int p[MAXN],sz[MAXN];
	ufds_() {
		FOR(i,0,MAXN-1) p[i]=i, sz[i]=1;
	}
	void merge(int x,int y){
		x=find(x),y=find(y);
		assert(x^y);
		p[x]=y, sz[y]+=sz[x];
	}
	int find(int x) { return (p[x]==x)?x:p[x]=find(p[x]); }
	ll get_sz(ll x) { return sz[find(x)]; }
} ufds;
ll nc2(ll n){ return n*(n-1); }
set<ll> v[MAXN],bck[MAXN];
map<ll,ll>howmany[MAXN];
queue<pi> q;
int main(){
	FAST
	cin>>n>>m;
	auto solve=[&](ll a,ll b){
		if(a==b)return;
		assert(v[a].count(b)), assert(v[b].count(a));
		v[a].erase(b), v[b].erase(a);
		ans-=nc2(ufds.get_sz(b)), ans-=nc2(ufds.get_sz(a)), ans+=nc2(ufds.get_sz(a)+ufds.get_sz(b));
		ans-=ufds.get_sz(a)*howmany[a][b], ans-=ufds.get_sz(b)*howmany[b][a];
		// assert(howmany[b][a]==0);
		// check if need swap;
		if(siz(v[a])+siz(bck[a])>siz(v[b])+siz(bck[b]))swap(a,b);
		// swap(a,b);
		fake[b]+=howmany[b][a], howmany[b][a]=0;
		for(auto i:v[a]) {
			assert(i==ufds.find(i));
			howmany[i][b]+=howmany[i][a];
			howmany[i].erase(a);
			v[b].ins(i);
			if(v[i].count(b)) {
				q.emplace(b, i);
			}
		}
		v[a].clear();
		ans+=ufds.get_sz(a)*(siz(bck[b])-fake[b]);
		for(auto i:bck[a]){
			if(ufds.find(i)==b||ufds.find(i)==a) continue;
			if(v[b].count(ufds.find(i))){
				q.emplace(b, i);
			}
			v[ufds.find(i)].erase(a), v[ufds.find(i)].ins(b);
			if(bck[b].find(i)!=bck[b].end()) ans-=ufds.get_sz(a);
			else bck[b].ins(i), howmany[b][ufds.find(i)]++, ans+=ufds.get_sz(b);
		}
		howmany[a].clear();
		bck[a].clear();
		deg[b]+=deg[a];
		ufds.merge(a,b);
	};
	FOR(i,1,m){
		ll a,b;cin>>a>>b;
		ll oa=a;
		a=ufds.find(a), b=ufds.find(b);
		if(a==b){
			cout<<ans<<'\n';
			continue;
		}
		if(v[b].find(a)!=v[b].end()){
			assert(bck[b].find(oa)==bck[b].end());
			v[a].ins(b);
			bck[b].ins(oa);
			++ howmany[b][a];
			ans+=ufds.get_sz(b);
			q.emplace(a, b);
			while(q.size()){
				solve(ufds.find(q.front().f),ufds.find(q.front().s));
				q.pop();
			}
		}else{
			if(bck[b].find(oa)==bck[b].end()){
				v[a].ins(b), bck[b].ins(oa);
				++ deg[a], ++deg[b];
				++ howmany[b][a]; // [receiving end][giving end]
				ans+=ufds.get_sz(b);
			}
		}
		cout<<ans<<'\n';
	}
}
/*
3 4
3 2
1 3
2 1
1 2
*/

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