Submission #881063

#	Time	Username	Problem	Language	Result	Execution time	Memory
881063		Cyber_Wolf	Papričice (COCI20_papricice)	C++17	110 / 110	288 ms	41296 KiB

papricice

#include <bits/stdc++.h>

using namespace std;

#define lg long long 
#define fastio ios_base::sync_with_stdio(0);cin.tie(NULL);cout.tie(NULL);

const lg N = 5e5+5;

vector<lg> adj[N], late;
lg sz[N], ans = N, n;
multiset<lg> se1, se2;

void dfs(lg src, lg par = -1)
{
	sz[src] = 1;
	for(auto it : adj[src])
	{
		if(it == par)	continue;
		dfs(it, src);
		sz[src] += sz[it];
	}
	return;
}

lg cost(lg a, lg b, lg c)
{
	return max({abs(a-b), abs(a-c), abs(b-c)});
}

void dfs2(lg src, lg par = -1)
{
	se1.insert(sz[src]);
	auto it = se1.lower_bound(n/2+sz[src]/2);
	lg z = n;
	if(it != se1.end())
	{
		z = (*it);
	}
	if(it != se1.begin())
	{
		it--;
		if(cost(sz[src], n-(*it), (*it)-sz[src]) <= cost(sz[src], n-z, z-sz[src]))
		{
			z = (*it);
		}
	}
	ans = min(ans, cost(sz[src], n-z, z-sz[src]));
	it = se2.lower_bound((n-sz[src])/2);
	z = n;
	if(it != se2.end())
	{
		z = (*it);
	}
	if(it != se2.begin())
	{
		it--;
		if(cost(sz[src], n-sz[src]-(*it), (*it)) <= cost(sz[src], n-z-sz[src], z))
		{
			z = (*it);
		}
	}
	ans = min(ans, cost(sz[src], z, n-z-sz[src]));
	for(auto it : adj[src])
	{
		if(it == par)	continue;
		while(late.size())
		{
			se2.insert(late.back());
			late.pop_back();
		}
		dfs2(it, src);
	}
	se1.erase(se1.find(sz[src]));
	late.push_back(sz[src]);
	return;
}

int main()
{
	fastio;
	cin >> n;
	for(int i = 1; i < n; i++)
	{
		lg u, v;
		cin >> u >> v;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}
	dfs(1);
	dfs2(1);
	late.clear();
	se2.clear();
	se1.clear();
	for(int i = 1; i <= n; i++)	reverse(adj[i].begin(), adj[i].end());
	dfs2(1);
	cout << ans << '\n';
}

• Subtask 1: 15 / 15
• Subtask 2: 35 / 35
• Subtask 3: 60 / 60