Submission #595719

#	Time	Username	Problem	Language	Result	Execution time	Memory
595719		penguinhacker	Meetings 2 (JOI21_meetings2)	C++17	0 / 100	3 ms	4948 KiB

meetings2

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

#define ll long long
#define ar array

const int mxN=2e5;
int n, d[mxN], s[mxN], anc[mxN][18], ans[mxN+1], tin[mxN], tout[mxN], t;
vector<int> adj[mxN];
set<ar<int, 2>> active;

void dfs(int u=0) {
	s[u]=1;
	tin[u]=t++;
	for (int i=1; i<18; ++i)
		anc[u][i]=anc[anc[u][i-1]][i-1];
	for (int v : adj[u])
		if (v!=anc[u][0]) {
			d[v]=d[u]+1, anc[v][0]=u;
			dfs(v);
			s[u]+=s[v];
		}
	tout[u]=t-1;
}

bool ia(int u, int v) {
	return tin[u]<=tin[v]&&tout[v]<=tout[u];
}

int lca(int u, int v) {
	if (ia(u, v)||ia(v, u))
		return ia(u, v)?u:v;
	for (int i=17; ~i; --i)
		if (!ia(anc[u][i], v))
			u=anc[u][i];
	return anc[u][0];
}

int dist(int u, int v) {
	return d[u]+d[v]-2*d[lca(u, v)];
}

int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cin >> n;
	for (int i=1; i<n; ++i) {
		int u, v;
		cin >> u >> v, --u, --v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
	dfs();
	vector<ar<int, 2>> upd;
	for (int i=1; i<n; ++i)
		upd.push_back({s[i], i});
	sort(upd.begin(), upd.end());
	fill(ans, ans+n+1, 1);
	int best=1;
	for (int i=n/2; i; --i) {
		while(upd.size()&&upd.back()[0]>=i) {
			int u=upd.back()[1];
			upd.pop_back();
			/*auto it=active.lower_bound({tin[u]});
			if (it!=active.begin()) {
				--it;
				int v=(*it)[1];
				if (tin[u]+s[u]<=tin[v]+s[v])
					active.erase(it);
			}*/
			for (auto it=active.begin(); it!=active.end();) {
				if (ia((*it)[1], u))
					it=active.erase(it);
				else
					++it;
			}
			for (ar<int, 2> x : active)
				best=max(best, dist(u, x[1])+1);
			active.insert({tin[u], u});
			for (ar<int, 2> x : active) {
				u=x[1];
				if (n-s[u]>=i) {
					int v=u;
					for (int j=17; ~j; --j)
						if (n-s[anc[v][j]]>=i)
							v=anc[v][j];
					best=max(best, d[u]-d[v]+2);
				}
			}
		}
		ans[2*i]=best;
	}
	for (int i=1; i<=n; ++i)
		cout << ans[i] << "\n";
	return 0;
}

• Subtask 1: 0 / 4
• Subtask 2: 0 / 16
• Subtask 3: 0 / 80