Submission #987059

#	Time	Username	Problem	Language	Result	Execution time	Memory
987059		Pyqe	Thousands Islands (IOI22_islands)	C++17	35 / 100	127 ms	39172 KiB

islands

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

using namespace std;

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

long long n,m,dh[100069],an[100069],cyc[100069];
vector<pair<long long,long long>> al[100069],nx[100069],nx2[100069];
vector<long long> vl[100069];
bitset<100069> vtd,vtd2;
pair<long long,long long> pr[100069];

void dfs(long long x)
{
	long long i,j,sz=al[x].size(),sz2,k,l,p;
	
	vtd[x]=1;
	vtd2[x]=1;
	for(i=0;i<sz;i++)
	{
		l=al[x][i].fr;
		p=al[x][i].sc;
		if(!vtd[l])
		{
			dh[l]=dh[x]+1;
			pr[l]={x,p};
			dfs(l);
		}
		if(vtd2[l])
		{
			if(dh[l]>dh[an[x]])
			{
				an[x]=l;
				nx[x]={{l,p}};
			}
		}
		else
		{
			cyc[x]=min(cyc[x]+cyc[l],2ll);
			if(cyc[l])
			{
				nx2[x].push_back({l,p});
			}
			if(vl[x].empty())
			{
				if(dh[an[l]]>dh[an[x]])
				{
					an[x]=an[l];
					nx[x]={{l,p}};
				}
			}
			else
			{
				if(!cyc[l])
				{
					cyc[x]=min(cyc[x]+1,2ll);
					nx[x].push_back({l,p});
				}
				sz2=vl[x].size();
				for(j=0;j<sz2;j++)
				{
					k=vl[x][j];
					cyc[k]=max(cyc[k],1ll);
				}
				vl[x].clear();
			}
		}
	}
	vtd2[x]=0;
	if(vtd2[an[x]])
	{
		vl[an[x]].push_back(x);
	}
}

variant<bool,vector<int>> find_journey(int on,int om,vector<int> ka,vector<int> la)
{
	long long i,k,l;
	
	n=on;
	m=om;
	for(i=1;i<=m;i++)
	{
		k=ka[i-1]+1;
		l=la[i-1]+1;
		al[k].push_back({l,i});
	}
	dh[0]=-1;
	dfs(1);
	if(cyc[1]!=2)
	{
		return false;
	}
	return true;
}

• Subtask 1: 1.75 / 5
• Subtask 2: 1.75 / 5
• Subtask 3: 7.35 / 21
• Subtask 4: 8.399999999999999 / 24
• Subtask 5: 15.749999999999998 / 45