Submission #447847

#	Time	Username	Problem	Language	Result	Execution time	Memory
447847		Jasiekstrz	Planine (COCI21_planine)	C++17	110 / 110	474 ms	61056 KiB

Main

#include<bits/stdc++.h>
#define fi first
#define se second
using namespace std;
const int N=1e6;
struct Point
{
	long long x,y;
};
Point operator-(Point a,Point b)
{
	return {a.x-b.x,a.y-b.y};
}
long long operator*(Point a,Point b)
{
	return a.x*b.y-a.y*b.x;
}
struct Quo
{
	long long x,y;
	bool operator<(const Quo &oth) const
	{
		return (__int128)x*oth.y<(__int128)oth.x*y;
	}
	bool operator<=(const Quo &oth) const
	{
		return (__int128)x*oth.y<=(__int128)oth.x*y;
	}
};
Point tab[N+10];
pair<Quo,Quo> seg[N+10];
set<Quo> st;
vector<Point> stck;
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int n,h;
	cin>>n>>h;
	for(int i=1;i<=n;i++)
		cin>>tab[i].x>>tab[i].y;
	int m=(n-2)/2;

	for(int i=2;i<n;i++)
	{
		if(i%2==0)
		{
			while(stck.size()>2)
			{
				auto tp=stck.back();
				stck.pop_back();
				if((tab[i]-stck.back())*(tp-stck.back())>0)
				{
					stck.push_back(tp);
					break;
				}
			}
			stck.push_back(tab[i]);
		}
		else
		{
			while(stck.size()>2)
			{
				auto tp=stck.back();
				stck.pop_back();
				if((tp-tab[i])*(stck.back()-tab[i])>0)
				{
					stck.push_back(tp);
					break;
				}
			}
			seg[i/2].fi=
			{tab[i].x*(stck.back().y-tab[i].y)+(stck.back().x-tab[i].x)*(h-tab[i].y),
				(stck.back().y-tab[i].y)};
		}
	}

	stck.clear();
	for(int i=n-1;i>1;i--)
	{
		if(i%2==0)
		{
			while(stck.size()>2)
			{
				auto tp=stck.back();
				stck.pop_back();
				if((tab[i]-stck.back())*(tp-stck.back())<0)
				{
					stck.push_back(tp);
					break;
				}
			}
			stck.push_back(tab[i]);
		}
		else
		{
			while(stck.size()>2)
			{
				auto tp=stck.back();
				stck.pop_back();
				if((tp-tab[i])*(stck.back()-tab[i])<0)
				{
					stck.push_back(tp);
					break;
				}
			}
			seg[i/2].se=
			{tab[i].x*(stck.back().y-tab[i].y)+(stck.back().x-tab[i].x)*(h-tab[i].y),
				(stck.back().y-tab[i].y)};
		}
	}

	//for(int i=3;i<n;i+=2)
	//{
	//	seg[i/2].fi=
	//	{(long long)tab[i].x*(tab[i-1].y-tab[i].y)+(long long)(tab[i-1].x-tab[i].x)*(h-tab[i].y),
	//		(tab[i-1].y-tab[i].y)};
	//	seg[i/2].se=
	//	{(long long)tab[i].x*(tab[i+1].y-tab[i].y)+(long long)(tab[i+1].x-tab[i].x)*(h-tab[i].y),
	//		(tab[i+1].y-tab[i].y)};	
	//}

	//for(int i=1;i<=m;i++)
	//	cerr<<seg[i].fi.x<<"/"<<seg[i].fi.y<<" "<<seg[i].se.x<<"/"<<seg[i].se.y<<"\n";
	pair<Quo,Quo> curr=seg[1];
	for(int i=2;i<=m;i++)
	{
		auto it=st.lower_bound(seg[i].fi);
		if(it!=st.end() && *it<=seg[i].se)
			continue;
		if(curr.se<seg[i].fi)
		{
			st.insert(curr.se);
			curr=seg[i];
		}
		else
		{
			curr.fi=max(curr.fi,seg[i].fi);
			curr.se=min(curr.se,seg[i].se);
		}
	}
	cout<<st.size()+1<<"\n";
	return 0;
}

• Subtask 1: 20 / 20
• Subtask 2: 30 / 30
• Subtask 3: 60 / 60