Submission #43740

#	Time	Username	Problem	Language	Result	Execution time	Memory
43740		MatheusLealV	Port Facility (JOI17_port_facility)	C++14	22 / 100	59 ms	17004 KiB

port_facility

#include <bits/stdc++.h>
#define N 3001
#define mod (1000000000 + 7)
#define f first
#define s second
using namespace std;
typedef pair<int, int> pii;

int n, ans, block[N][N], cor[N], qtd, pot[N], edge = 0;

pii v[N];

bool nope = false;

vector<int> grafo[N];

struct line
{
	int pos, id, tip;

	bool operator < (const line &ll) const
	{
		if(pos != ll.pos) return pos < ll.pos;

		return tip > ll.tip;
	}
};

vector<line> sweep;

bool cmp(pii a, pii b)
{
	if(a.f != b.f) return a.f < b.f;

	return a.s > b.s;
}

bool intersect(int i, int j)
{
	if(v[j].f < v[i].f) swap(i, j);

	if(v[i].f <= v[j].f && v[j].s <= v[i].s) return false;

	if(v[i].f < v[j].f && v[j].f < v[i].s) return true;

	return false;
}

void dfs_color(int x)
{
	for(auto v: grafo[x])
	{
		if(cor[v] == cor[x])
		{
			nope = true;

			return;
		}

		if(cor[v] != -1) continue;

		cor[v] = (cor[x] + 1)%2;

		dfs_color(v);
	}
}

int main()
{
	ios::sync_with_stdio(false); cin.tie(0);

	cin>>n;

	for(int i = 1; i <= n; i++)
	{
		cin>>v[i].f>>v[i].s;

		sweep.push_back( { v[i].f, i, 0 } );

		sweep.push_back( { v[i].s, i, 1 } );
	}

	sort(sweep.begin(), sweep.end());

	set< pii > open;

	for(int i = 0; i < sweep.size(); i++)
	{
		int x = sweep[i].pos, id = sweep[i].id, tip = sweep[i].tip;

		if(!tip)
		{
			open.insert( {x, id} );
		}

		else
		{
			open.erase( {v[id].f, id } );

			if(open.size())
			{
				auto it = open.begin();

				int ini = (*it).f, jd = (*it).s;

				if(v[id].f < ini && ini < x)
				{
					edge ++;

					grafo[id].push_back(jd);

					grafo[jd].push_back(id);
				}

			}

			for(auto it = open.upper_bound( {x, 0} ); it != open.begin() ; it--)
			{
				int ini = (*it).f, jd = (*it).s;

				if(it == open.end()) continue;

				if(v[id].f < ini && ini < x)
				{
					edge ++;

					grafo[id].push_back(jd);

					grafo[jd].push_back(id);
				}
			}
		}
	}

	pot[0] = 1;

	for(int i = 1; i <= n; i++) pot[i] = (2*pot[i - 1])%mod;

	memset(cor, -1, sizeof cor);
	
	for(int i = 1; i <= n; i++)
	{
		if(cor[i] == -1)
		{
			qtd ++;

			cor[i] = 0;

			dfs_color(i);
		}
	}

	cout<<(nope ? 0 : pot[qtd])<<"\n";
}

Compilation message (stderr)

port_facility.cpp: In function 'int main()':
port_facility.cpp:87:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < sweep.size(); i++)
                   ^

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 0 / 56
• Subtask 4: 0 / 22