Submission #924914

#	Time	Username	Problem	Language	Result	Execution time	Memory
924914		Faisal_Saqib	Cat in a tree (BOI17_catinatree)	C++17	0 / 100	2 ms	9816 KiB

catinatree

#include <iostream>
#include <vector>
#include <bitset>
#include <queue>
using namespace std;
const int N=2e5+10;
int n,d;
vector<int> ma[N],vep[N];
int h[N],dist[N],root[N];
bitset<N> rem;
bitset<N> vis;
bitset<N> kill;
int main()
{
	cin.tie(0);
	cout.tie(0);
	ios::sync_with_stdio(0);
	cin>>n>>d;
	if(d==1)
	{
		cout<<n<<endl;
		return 0;
	}
	vep[0].push_back(1);
	int max_h=0;
	for(int i=2;i<=n;i++)
	{
		int p;
		cin>>p;
		p++;
		h[i]=h[p]+1;
		vep[h[i]].push_back(i);
		max_h=max(max_h,h[i]);
		ma[p].push_back(i);
		ma[i].push_back(p);
	}
	int ans=0;
	for(int i=1;i<=n;i++)
		dist[i]=1e6;
	for(int cur_h=max_h;cur_h>=0;cur_h--)
	{
		queue<int> q;
		int st=0;
		for(int v:vep[cur_h])
		{
			if(!rem[v])
			{
				q.push(v);
				root[v]=v;
				st++;
				dist[v]=0;
				vis.set(v);
			}
		}
		vector<int> visited;
		while(q.size())
		{
			int v=q.front();
			q.pop();
			if(dist[v]>=d)
				continue;
			visited.push_back(v);
			rem.set(v);
			for(int y:ma[v])
			{
				if(!vis[y])
				{
					dist[y]=dist[v]+1;
					q.push(y);
					root[y]=root[v];
					vis.set(y);
				}
				else if(dist[y]==dist[v]+1 and (dist[y]+dist[v]+1)<d and !kill[root[v]])
				{
					st--;
					kill[root[v]]=1;
				}
			}			
		}
		for(int u:visited)
			vis[u]=0;
		ans+=st;
	}
	cout<<ans<<'\n';
	return 0;
}

• Subtask 1: 0 / 11
• Subtask 2: 0 / 40
• Subtask 3: 0 / 49