Submission #693846

#	Time	Username	Problem	Language	Result	Execution time	Memory
693846		Pyqe	Thousands Islands (IOI22_islands)	C++17	1.75 / 100	37 ms	11772 KiB

islands

#include <bits/stdc++.h>
#include "islands.h"

using namespace std;

#define mp make_pair
#define fr first
#define sc second

const long long inf=1e18;
long long n,m,dh[100069],dsu[100069],an[100069],dp[100069];
pair<long long,long long> ed[100069];
vector<long long> al[100069];
bitset<100069> vtd,vtd2;

long long fd(long long x)
{
	if(dsu[x]!=x)
	{
		dsu[x]=fd(dsu[x]);
	}
	return dsu[x];
}

void dfs(long long x)
{
	long long i,sz=al[x].size(),l;
	
	vtd[x]=1;
	vtd2[x]=1;
	an[x]=0;
	for(i=0;i<sz;i++)
	{
		l=al[x][i];
		if(!vtd[l])
		{
			dh[l]=dh[x]+1;
			dfs(l);
		}
		if(vtd2[l])
		{
			if(dh[l]>dh[an[x]])
			{
				an[x]=l;
			}
		}
		else if(an[l]&&vtd2[an[l]])
		{
			if(dh[an[l]]>dh[an[x]])
			{
				an[x]=an[l];
			}
		}
	}
	vtd2[x]=0;
}

void dfs2(long long x)
{
	long long i,sz=al[x].size(),l;
	
	vtd[x]=1;
	vtd2[x]=1;
	dp[x]=!!an[x];
	for(i=0;i<sz;i++)
	{
		l=al[x][i];
		if(!vtd[l])
		{
			dfs2(l);
		}
		if(!vtd2[l])
		{
			if(dp[x]==2&&dp[l]==2)
			{
				dp[x]=2;
			}
			else if(!an[l]||!vtd2[an[l]])
			{
				dp[x]=min(dp[x]+dp[l],2ll);
			}
		}
	}
	vtd2[x]=0;
}

variant<bool,vector<int>> find_journey(int on,int om,vector<int> ka,vector<int> la)
{
	long long i,k,l;
	variant<bool,vector<int>> sq;
	
	n=on;
	m=om;
	for(i=1;i<=m;i++)
	{
		k=ka[i-1]+1;
		l=la[i-1]+1;
		ed[i]={k,l};
		al[k].push_back(l);
	}
	dh[0]=-inf;
	dfs(1);
	vtd.reset();
	dfs2(1);
	return dp[1]==2;
}

• Subtask 1: 0 / 5
• Subtask 2: 1.75 / 5
• Subtask 3: 0 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 45