Submission #127174

#	Time	Username	Problem	Language	Result	Execution time	Memory
127174		baluteshih	Port Facility (JOI17_port_facility)	C++14	0 / 100	27 ms	27768 KiB

port_facility

#include <bits/stdc++.h>
#define jizz ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define pb push_back
#define MP make_pair
#define F first
#define S second
#define MEM(i,j) memset(i,j,sizeof i)
#define ALL(v) v.begin(),v.end()
#define ET cout << "\n"
#define DB(a,s,e) {for(int i=s;i<e;++i) cout << a[i] << " ";ET;}
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

const ll MOD=1e9+7;
vector<int> G[1000005];
map<int,int> mp;
pii seg[1000005];
int color[1000005];

bool dfs(int u,int c)
{
	color[u]=c;
	for(int i:G[u])
		if(!~color[i]&&!dfs(i,c^1))
			return 0;
		else if(color[i]==color[u])
			return 0;
	return 1;
}

int main()
{jizz
	int n,cnt=0,flag=1,ans=1;
	cin >> n;
	for(int i=0;i<n;++i)
		cin >> seg[i].F >> seg[i].S;
	sort(seg,seg+n),MEM(color,-1);
	for(int i=0;i<n&&flag;++i)
	{
		int w[2]={},yes=0;
		for(int j=0;j<i;++j)
			if(seg[j].S>seg[i].F&&seg[i].S>seg[j].S)
				if(~color[j])
					w[color[j]]=1;
				else yes=1;
		if(w[0]&&w[1]) flag=0;
		else if(w[0]||w[1])
		{
			color[i]=w[0]?1:0;
			for(int j=0;j<i;++j)
				if(seg[j].S>seg[i].F&&seg[i].S>seg[j].S)
					if(!~color[j])
						color[j]=color[i]^1;
		}
		else if(yes)
		{
			ans=ans*2%MOD;
			color[i]=0;
			for(int j=0;j<i;++j)
				if(seg[j].S>seg[i].F&&seg[i].S>seg[j].S)
					color[j]=1;
		}
	}
	if(flag)
		for(int i=0;i<n;++i)
			if(!~color[i])
				ans=ans*2%MOD;
	if(flag) cout << ans << "\n";
	else cout << "0\n";
}

Compilation message (stderr)

port_facility.cpp: In function 'int main()':
port_facility.cpp:44:6: warning: suggest explicit braces to avoid ambiguous 'else' [-Wdangling-else]
    if(seg[j].S>seg[i].F&&seg[i].S>seg[j].S)
      ^
port_facility.cpp:35:8: warning: unused variable 'cnt' [-Wunused-variable]
  int n,cnt=0,flag=1,ans=1;
        ^~~

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