Submission #1253496

#	Time	Username	Problem	Language	Result	Execution time	Memory
1253496		thdh__	Meetings 2 (JOI21_meetings2)	C++20	100 / 100	456 ms	31256 KiB

meetings2

#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, ans[N];
vector<int> adj[N];

int sz[N];
bool check[N];

void predfs(int u, int p) 
{
	sz[u] = 1;
	for (auto v : adj[u]) 
	{
		if (v == p || check[v]) continue;
		predfs(v, u);
		sz[u] += sz[v];
	}
}

int centroid(int u, int p, int siz) 
{
	for (auto v : adj[u]) 
	{
		if (v == p || check[v]) continue;
		if (sz[v] * 2 > siz) return centroid(v, u, siz);
	}
	return u;
}

vector<ii> a;
int mx[N];
ii best[N];

void dfs(int u, int p, int depth) 
{
	sz[u] = 1;
	for (auto v : adj[u]) 
	{
		if (v == p || check[v]) continue;
		dfs(v, u, depth+1);
		sz[u] += sz[v];
	}
	a.pb({sz[u], depth});
}

void decomp(int u) 
{
	predfs(u, 0);
	int c = centroid(u, 0, sz[u]);
	// cout<<"Centroid: "<<c<<endl;
	for (int i = 1; i <= sz[u]; i++) best[i] = {0, 0};
	for (auto v : adj[c]) 
	{
		if (check[v]) continue;
		dfs(v, c, 1);
		// cout<<"Branch "<<v<<endl;
		for (int i = 1; i <= sz[v]; i++) mx[i] = 0;
		for (auto i : a) mx[i.fi] = max(mx[i.fi], i.se);
		// for (auto i : a) cout<<i.fi<<" "<<i.se<<endl;
		// cout<<endl;
		mx[sz[v]+1] = 0;
		for (int i = sz[v]; i >= 0; i--) 
		{
			mx[i] = max(mx[i], mx[i+1]);
			// cout<<mx[i]<<" ";
			if (mx[i] > best[i].fi) best[i].se = best[i].fi, best[i].fi = mx[i];
			else if (mx[i] > best[i].se) best[i].se = mx[i];
		}
		// cout<<endl;
		a.clear();
	}
	check[c] = 1;
	// cout<<endl;
	// for (int i = 1; i <= sz[c]; i++) cout<<best[i].fi<<" "<<best[i].se<<endl;
	// cout<<endl;
	for (int i = 1; i <= sz[c]; i++) ans[i] = max(ans[i], best[i].fi + best[i].se);
	for (auto v : adj[c]) 
	{
		if (check[v]) continue;
		decomp(v);
	}
}

void solve()
{
	cin>>n;
	for (int i = 1; i < n; i++) 
	{
		int u,v; cin>>u>>v;
		adj[u].pb(v); adj[v].pb(u);
	}
	decomp(1);
	for (int i = 1; i <= n; i++) 
	{
		if (i % 2 == 1) cout<<1<<endl;	
		else cout<<ans[i/2]+1<<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: 4 / 4
• Subtask 2: 16 / 16
• Subtask 3: 80 / 80