제출 #1254361

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1254361		thdh__	조이터에서 친구를 만드는건 재밌어 (JOI20_joitter2)	C++20	100 / 100	721 ms	80260 KiB

joitter2

#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define fi first
#define se second
#define all(a) a.begin(),a.end()
#define bruh ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fu(x,a,b) for (auto x=a;x<=b;x++)
#define fd(x,a,b) for (auto x=a;x>=b;x--)
#define int ll

using namespace std;
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());

/*
Competitive Programming notes that I need to study & fix my dumbass self:

1. Coding:
- Always be sure to check the memory of arrays (maybe use vectors), for loops
- Always try to maximize the memory if possible, even if you are going for subtasks
- Do not exploit #define int long long, it will kill you

2. Stress: 
- Always try generating big testcases and try if they run

3. Time management:
- Don't overcommit or undercommit, always spend a certain amount of time to think a problem, don't just look at it and say I'm fucked
- Do not spend too much time coding brute-force solutions, they should be easily-codable solutions that don't take up too much time

Time management schedule:
Offline / LAH days (4 problems - 3h):
15' thinking of solution / idea
1. no idea: skip
2. yes idea: continue thinking for <= 15'

+ implementing: <= 20'
+ brute-force: <= 5'
+ test generator: <= 5'

I hate offline because I am dumb
*/

typedef pair<int, int> ii;
const int N = 2e5+5;
const int B = 750;
const int mod = 1e9+7;
const int inf = 1e18;
using cd = complex<double>;
const long double PI = acos(-1);
int power(int a,int b) {ll x = 1;if (a >= mod) a%=mod; while (b) {if (b & 1) x = x*a % mod;a = a*a % mod;b>>=1;}return x;} 

int n,m,ans = 0;
set<int> adj[N], rev[N], ch[N];
int par[N], sz[N];
queue<ii> q;

void add_edge(int a, int b) 
{
	adj[a].insert(b); rev[b].insert(a);
	if (adj[b].find(a) != adj[b].end()) q.push({a,b});
}

int find(int u) 
{
	if (u == par[u]) return u;
	par[u] = find(par[u]);
	return par[u];
}

void merge(int u, int v) 
{
	u = find(u), v = find(v);
	if (u == v) return;
	if ((ch[u].size() + adj[u].size() + rev[u].size()) < (ch[v].size() + adj[v].size() + rev[v].size())) swap(u,v);
	par[v] = u;
	ans += sz[u] * ch[v].size() + sz[v] * ch[u].size();
	sz[u] += sz[v];
	for (auto i : ch[v]) {
		if (ch[u].count(i)) ans -= sz[u];
		else ch[u].insert(i);
	}
	adj[u].erase(v), rev[u].erase(v);
	adj[v].erase(u), rev[v].erase(u);
	for (auto i : adj[v]) 
	{
		rev[i].erase(v);
		add_edge(u, i);
	}
	for (auto i : rev[v]) 
	{
		adj[i].erase(v);
		add_edge(i, u);
	}
}

void solve()
{
	cin>>n>>m;
	for (int i = 1; i <= n; i++) par[i] = i, sz[i] = 1, ch[i].insert(i);
	for (int i = 0; i < m; i++) 
	{
		int a,b; cin>>a>>b;
		b = find(b);
		if (find(a) != b && ch[b].find(a) == ch[b].end())
		{
			ch[b].insert(a);
			ans += sz[b];
			a = find(a);
			add_edge(find(a), find(b));
			while (!q.empty()) 
			{
				merge(q.front().fi, q.front().se);
				q.pop();
			}
		}	
		cout<<ans<<endl;
	}
}

/*
Go through the mistakes you usually make and revise your code, for god's sake...
*/

signed main()
{
	bruh
	//freopen("input.inp","r",stdin);
	//freopen("output.inp","w",stdout);
	int t = 1;
	// cin>>t;
	while (t--)
	{
		solve();
		cout<<"\n";
	}
}

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