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답안 #924946

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
924946 2024-02-10T05:50:51 Z Faisal_Saqib Cat in a tree (BOI17_catinatree) C++17
0 / 100
 3 ms 14684 KB 
#include <iostream>
#include <vector>
#include <bitset>
#include <map>
using namespace std;
const int N=2e5+10;
const int LG=18;
int n,d;
int pw2[LG];
int par[N][LG];
vector<int> ma[N],vep[N];
int part[N];
int h[N],dist[N],sz[N];
bitset<N> dead;
int cn;
void dfs(int&x,int p=0)
{
	sz[x]=1;
	par[x][0]=p;
	for(int j=1;j<LG;j++)
		par[x][j]=par[par[x][j-1]][j-1];
	for(int&y:ma[x])
	{
		if(y!=p)
		{
			dfs(y,x);
			sz[x]+=sz[y];
		}
	}
}
int find_centriod(int&x,int p=0)
{
	for(int&y:ma[x])
	{
		if(y!=p and !dead[y] and sz[y]>(cn/2))
		{
			sz[x]-=sz[y];
			sz[y]+=sz[x];
			return find_centriod(y,x);
		}
	}
	return x;
}
int solve(int&x)
{
	cn=sz[x];
	int c=find_centriod(x);
	dead[c]=1;
	for(int&y:ma[c])
		if(!dead[y])
			part[solve(y)]=c;
	return c;
}
// map<pair<int,int>,int> memo;
int dist1(int x,int y)
{
	if(h[x]<h[y])
		swap(x,y);
	int ans=0;
	for(int j=LG-1;j>=0;j--)
	{
		if(h[par[x][j]]>=h[y])
		{
			ans+=pw2[j];
			x=par[x][j];
		}
	}
	for(int j=LG-1;j>=0;j--)
	{
		if(par[x][j]!=par[y][j])
		{
			x=par[x][j];
			y=par[y][j];
			ans+=pw2[j];
			ans+=pw2[j];
		}
	}
	// cout<<"Distance btw "<<x<<' '<<y<<' ';
	// cout<<ans+(x!=y)<<endl;
	return ans+(x!=y);
}
void color(int&st)
{
	// cout<<"Marked "<<st<<endl;
	int x=st;
	while(x>0)
	{
		dist[x]=min(dist[x],dist1(x,st));	
		x=part[x];
	}
}
int query(int&st)
{
	int x=st;
	int ans=dist[x];
	while(x>0)
	{
		ans=min(ans,dist1(x,st)+dist[x]);
		x=part[x];
	}
	return ans;
}
int main()
{
	cin.tie(0);
	cout.tie(0);
	ios::sync_with_stdio(0);
	pw2[0]=1;
	for(int i=1;i<LG;i++)
		pw2[i]=(pw2[i-1]*2);
	cin>>n>>d;
	h[1]=1;
	vep[1].push_back(1);
	int max_h=1;
	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 j=1;j<=n;j++)
		dist[j]=1e9;
	int o_1=1;
	dfs(o_1);
	solve(o_1);
	for(int cur_h=max_h;cur_h>=1;cur_h--)
	{
		for(int&v:vep[cur_h])
		{
			if(query(v)>=d)
			{
				ans++;
				color(v);
			}
		}
	}
	cout<<ans<<'\n';
	return 0;
}

Subtask #1
0 / 11.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 14684 KB Output is correct
2 Incorrect 3 ms 14684 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #2
0 / 40.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 14684 KB Output is correct
2 Incorrect 3 ms 14684 KB Output isn't correct
3 Halted 0 ms 0 KB -

Subtask #3
0 / 49.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 14684 KB Output is correct
2 Incorrect 3 ms 14684 KB Output isn't correct
3 Halted 0 ms 0 KB -