QOJ.ac

QOJ

The 2nd Universal Cup Finals is coming! Check out our event page, schedule, and competition rules!

ID	Problem	Submitter	Result	Time	Memory	Language	File size	Submit time	Judge time
#419222	#8720. BFS 序 0	tzxydby	WA	186ms	61252kb	C++20	2.1kb	2024-05-23 19:04:35	2024-05-23 19:07:57

Judging History

This is the latest submission verdict.

[2024-05-23 19:07:57]
Judged

Verdict: WA
Time: 186ms
Memory: 61252kb

Show

[2024-05-23 19:04:35]
Submitted

answer

#include<bits/stdc++.h>
using namespace std;
const int N=500005;
int n,m,q,fa[N][20],dep[N],a[N],d[N],dfn[N],low[N],tim,in[N],st[N],tp,ok,vis[N];
vector<int>e[N],g[N],p;
void dfs(int u,int f)
{
	fa[u][0]=f;
	dep[u]=dep[f]+1;
	for(auto v:e[u])
		if(v!=f)
			dfs(v,u);
}
int lca(int u,int v)
{
	if(dep[u]<dep[v])
		swap(u,v);
	for(int i=18;i>=0;i--)
		if(dep[fa[u][i]]>=dep[v])
			u=fa[u][i];
	if(u==v)
		return u;
	for(int i=18;i>=0;i--)
		if(fa[u][i]!=fa[v][i])
			u=fa[u][i],v=fa[v][i];
	return fa[u][0];
}
int cal(int u,int v)
{
	for(int i=18;i>=0;i--)
		if(dep[fa[u][i]]>dep[v])
			u=fa[u][i];
	return u;
}
void tarjan(int u)
{
	dfn[u]=low[u]=++tim;
	st[++tp]=u,in[u]=1;
	for(auto v:g[u])
	{
		if(!dfn[v])
		{
			tarjan(v);
			low[u]=min(low[u],low[v]);
		}
		else if(in[v])
			low[u]=min(low[u],dfn[v]);
	}
	if(dfn[u]==low[u])
	{
		int v;
		do
		{
			v=st[tp--];
			in[v]=0;
			if(v!=u)
				ok=0;
		}while(v!=u);
	}
}
int main()
{
	scanf("%d",&n);
	for(int i=2;i<=n;i++)
	{
		int x;
		scanf("%d",&x);
		e[x].push_back(i);
	}
	dfs(1,0);
	for(int j=1;j<=18;j++)
		for(int i=1;i<=n;i++)
			fa[i][j]=fa[fa[i][j-1]][j-1];
	scanf("%d",&q);
	while(q--)
	{
		scanf("%d",&m);
		for(int i=1;i<=m;i++)
			scanf("%d",&a[i]);
		ok=1;
		for(int i=1;i<=m;i++)
		{
			if(vis[a[i]])
				ok=0;
			vis[a[i]]=1;
		}
		for(int i=1;i<=m;i++)
			vis[a[i]]=0;
		for(int i=1;i<=m;i++)
			d[i]=dep[a[i]];
		for(int i=1;i<m;i++)
			if(d[i]>d[i+1])
				ok=0;
		if(!ok)
		{
			puts("No");
			continue;
		}
		for(int i=1;i<=m;i++)
		{
			int j=i;
			while(j<m&&d[j+1]==d[i])
				j++;
			for(int k=i;k<j;k++)
			{
				int l=lca(a[k],a[k+1]);
				int u=cal(a[k],l),v=cal(a[k+1],l);
				p.push_back(u);
				p.push_back(v);
				g[u].push_back(v);
			}
			sort(p.begin(),p.end());
			p.erase(unique(p.begin(),p.end()),p.end());
			for(auto u:p)
				if(!dfn[u])
					tarjan(u);
			for(auto u:p)
			{
				g[u].clear();
				dfn[u]=low[u]=in[u]=0;
			}
			tim=tp=0;
			p.clear();
			i=j;
			if(!ok)
				break;
		}
		puts(ok?"Yes":"No");
	}
	return 0;
}

Source code, Language: C++20

Details

Tip: Click on the bar to expand more detailed information

Test #1:

score: 100

Accepted

time: 0ms

memory: 16016kb

input:

6
1 1 3 2 4
10
4 3 6 2 5
1 4
3 2 4 5
5 2 5 4 6 3
3 1 4 2
3 5 6 3
5 4 5 2 6 1
4 4 3 2 5
4 4 6 2 3
3 3 2 6

output:

No
Yes
Yes
No
No
No
No
No
No
Yes

result:

ok 10 token(s): yes count is 3, no count is 7

Test #2:

score: -100

Wrong Answer

time: 186ms

memory: 61252kb

input:

300000
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1...

output:

No
Yes
Yes
Yes
No
No
No
No
No
No
Yes
Yes
No
Yes
No
Yes
Yes
Yes
No
No
No
No
Yes
No
No
Yes
No
No
No
No
Yes
Yes
Yes
No
No
Yes
No
No
No
No
No
No
No
Yes
No
Yes
No
Yes
No
No
No
No
Yes
Yes
Yes
No
No
Yes
No
No
No
No
No
Yes
Yes
No
No
No
No
No
Yes
Yes
No
Yes
No
No
No
Yes
No
No
Yes
No
No
Yes
Yes
Yes
No
No
No
Y...

result:

wrong answer expected NO, found YES [181st token]