Submission #825017

#	Time	Username	Problem	Language	Result	Execution time	Memory
825017		MohamedAhmed04	Port Facility (JOI17_port_facility)	C++14	100 / 100	3899 ms	241072 KiB

port_facility

#include <bits/stdc++.h>

using namespace std ;

const int mod = 1e9 + 7 ;

int Add(int x , int y)
{
	int z = x + y ;
	if(z >= mod)
		z -= mod ;
	return z ;
}

int Sub(int x , int y)
{
	int z = x - y ;
	if(z < 0)
		z += mod ;
	return z ;
}

int Mul(int x , int y)
{
	return (1ll * x * y) % mod ;
}

int powlog(int base , int power)
{
	if(power == 0)
		return 1 ;
	int x = powlog(base , power / 2) ;
	if(power & 1)
		x = Mul(x , base) ;
	return x ;
}

const int MAX = 2e6 + 10 ;

int arr[MAX] ;
int n ;

int L[MAX] , R[MAX] ;
int to[MAX] , back[MAX] ;
int id[MAX] ;

pair<int , int>tree[2][4 * MAX] ;

void build(int node , int l , int r)
{
	if(l == r)
	{
		tree[0][node].first = to[l] ;
		tree[1][node].first = back[l] ;
		tree[0][node].second = tree[1][node].second = id[l] ;
		return ;
	}
	int mid = (l + r) >> 1 ;
	build(node << 1 , l , mid) ;
	build(node << 1 | 1 , mid+1 , r) ;
	tree[0][node] = max(tree[0][node << 1] , tree[0][node << 1 | 1]) ;
	tree[1][node] = min(tree[1][node << 1] , tree[1][node << 1 | 1]) ;
}

void update(int node , int l , int r , int idx , int val , bool t)
{
	if(idx > r || idx < l)
		return ;
	if(l == r)
	{
		tree[t][node].first = val ;
		return ;
	}
	int mid = (l + r) >> 1 ;
	update(node << 1 , l , mid , idx , val , t) ;
	update(node << 1 | 1 , mid+1 , r , idx , val , t) ;
	tree[0][node] = max(tree[0][node << 1] , tree[0][node << 1 | 1]) ;
	tree[1][node] = min(tree[1][node << 1] , tree[1][node << 1 | 1]) ;
}

pair<int , int>query(int node , int l , int r , int from , int to , bool t)
{
	if(from > r || to < l || from > to)
	{
		if(!t)
			return {-1e9 , -1e9} ;
		else
			return {1e9 , 1e9} ;
	}
	if(l >= from && r <= to)
		return tree[t][node] ;
	int mid = (l + r) >> 1 ;
	pair<int , int>a = query(node << 1 , l , mid , from , to , t) ;
	pair<int , int>b = query(node << 1 | 1 , mid+1 , r , from , to , t) ;
	if(!t)
		return max(a , b) ;
	else
		return min(a , b) ;
}

int vis[MAX] ;
vector< pair<int , int> >vp[2] ;

void dfs(int node , int col)
{
	vis[node] = 1 ;
	vp[col].emplace_back(L[node] , R[node]) ;
	update(1 , 1 , 2*n , L[node] , -1e9 , 0) ;
	update(1 , 1 , 2*n , R[node] , 1e9 , 1) ;
	bool ok = false ;
	while(!ok)
	{
		ok = true ;
		pair<int , int>p = query(1 , 1 , 2*n , L[node] , R[node] , 0) ;
		if(p.first > R[node])
			dfs(p.second , !col) , ok = false ;
		p = query(1 , 1 , 2*n , L[node] , R[node] , 1) ;
		if(p.first < L[node])
			dfs(p.second , !col) , ok = false ;
	}
}

bool check(bool t)
{
	sort(vp[t].begin() , vp[t].end()) ;
	set<int>s ;
	for(auto &p : vp[t])
	{
		auto it = s.lower_bound(p.second) ;
		if(it != s.begin())
		{
			it-- ;
			int x = *it ;
			if(p.first < x)
				return false ;
		}
		s.insert(p.second) ;
	}
	return true ;
}

int main()
{
	ios_base::sync_with_stdio(0) ;
	cin.tie(0) ;
	cin>>n ;
	for(int i = 1 ; i <= 2*n ; ++i)
		to[i] = -1e9 , back[i] = 1e9 ;
	for(int i = 1 ; i <= n ; ++i)
	{
		cin>>L[i]>>R[i] ;
		to[L[i]] = R[i] , back[R[i]] = L[i] ;
		id[L[i]] = id[R[i]] = i ;
	}
	build(1 , 1 , 2*n) ;
	int ans = 1 ;
	for(int i = 1 ; i <= n ; ++i)
	{
		if(vis[i])
			continue ;
		dfs(i , 0) ;
		ans = Mul(ans , 2) ;
	}
	if((!check(0)) || (!check(1)))
		ans = 0 ;
	return cout<<ans<<"\n" , 0 ;
}		

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