oj.uz

답안 #447956

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
447956 2021-07-28T09:22:25 Z Jasiekstrz Geometrija (COCI21_geometrija) C++17
50 / 110
 1000 ms 452 KB 
#include<bits/stdc++.h>
#define fi first
#define se second
using namespace std;
const int N=1e3;
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;
}
int sgn(long long x)
{
	return (x<0 ? -1:1);
}
int ilo(Point a,Point b,Point c)
{
	return sgn((a-c)*(b-c));
}
bool cross(Point a,Point b,Point c,Point d)
{
	return (ilo(c,b,a)!=ilo(d,b,a) && ilo(a,d,c)!=ilo(b,d,c));
}
bool inside(Point p,Point a,Point b,Point c)
{
	int val=sgn((p-a)*(b-a));
	if(sgn((p-b)*(c-b))==val && sgn((p-c)*(a-c))==val)
		return true;
	return false;
}
Point tab[N+10];
vector<int> hull;
bool onhull[N+10];
bool vis[N+10];
int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
	int n,ans=0;
	cin>>n;
	for(int i=1;i<=n;i++)
		cin>>tab[i].x>>tab[i].y;
	sort(tab+1,tab+n+1,[](Point a,Point b){ return a.x<b.x; });

	auto pop_bad=[](int x)
	{
		while(hull.size()>1 && 
				(tab[x]-tab[hull[hull.size()-2]])*(tab[hull.back()]-tab[hull[hull.size()-2]])<0)
			hull.pop_back();
		hull.push_back(x);
		return;
	};
	for(int i=1;i<=n;i++)
		pop_bad(i);
	for(int i=n-1;i>=1;i--)
		pop_bad(i);
	hull.pop_back();
	for(auto v:hull)
		onhull[v]=true;
	//for(auto v:hull)
	//	cerr<<tab[v].x<<" "<<tab[v].y<<"\n";

	for(int i=1;i<=n;i++)
	{
		if(onhull[i])
			continue;
		int a=1,b,c;
		for(b=1,c=2;sgn((tab[hull[b]]-tab[a])*(tab[i]-tab[a]))==
				sgn((tab[hull[c]]-tab[a])*(tab[i]-tab[a]));b++,c++);
		b=hull[b];
		c=hull[c];
		for(int j=1;j<=n;j++)
		{
			if(j==i || j==a || j==b || j==c || !inside(tab[j],tab[a],tab[b],tab[c]))
				continue;
			if(inside(tab[i],tab[a],tab[b],tab[j]))
				c=j;
			else if(inside(tab[i],tab[a],tab[j],tab[c]))
				b=j;
			else if(inside(tab[i],tab[j],tab[b],tab[c]))
				a=j;
		}
		for(int j:{a,b,c})
		{
			//cerr<<tab[i].x<<","<<tab[i].y<<" "<<tab[j].x<<","<<tab[j].y<<"\n";
			if(vis[j])
				continue;
			bool ok=true;
			for(int p=1;p<=n;p++)
			{
				if(p==i || p==j)
					continue;
				for(int q=p+1;q<=n;q++)
				{
					if(q!=i && q!=j && cross(tab[i],tab[j],tab[p],tab[q]))
					{
						//cerr<<tab[i].x<<","<<tab[i].y<<" "<<tab[j].x<<","<<tab[j].y<<" "
						//	<<tab[p].x<<","<<tab[p].y<<" "<<tab[q].x<<","<<tab[q].y<<"\n";
						ok=false;
						break;
					}
				}
				if(!ok)
					break;
			}
			if(ok)
				ans++;
		}
		vis[i]=true;
		//cerr<<tab[i].x<<" "<<tab[i].y<<" "<<ans<<"\n";
	}
	cout<<ans+hull.size()<<"\n";
	return 0;
}

Subtask #1
20.0 / 20.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 204 KB Output is correct
4 Correct 1 ms 204 KB Output is correct
5 Correct 1 ms 204 KB Output is correct
6 Correct 0 ms 204 KB Output is correct
7 Correct 1 ms 204 KB Output is correct
8 Correct 1 ms 204 KB Output is correct
9 Correct 1 ms 204 KB Output is correct
10 Correct 1 ms 320 KB Output is correct
11 Correct 1 ms 204 KB Output is correct

Subtask #2
30.0 / 30.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 204 KB Output is correct
4 Correct 1 ms 204 KB Output is correct
5 Correct 1 ms 204 KB Output is correct
6 Correct 0 ms 204 KB Output is correct
7 Correct 1 ms 204 KB Output is correct
8 Correct 1 ms 204 KB Output is correct
9 Correct 1 ms 204 KB Output is correct
10 Correct 1 ms 320 KB Output is correct
11 Correct 1 ms 204 KB Output is correct
12 Correct 6 ms 332 KB Output is correct
13 Correct 6 ms 204 KB Output is correct
14 Correct 4 ms 204 KB Output is correct
15 Correct 4 ms 204 KB Output is correct
16 Correct 1 ms 332 KB Output is correct
17 Correct 21 ms 324 KB Output is correct
18 Correct 18 ms 332 KB Output is correct
19 Correct 12 ms 332 KB Output is correct
20 Correct 62 ms 204 KB Output is correct
21 Correct 53 ms 204 KB Output is correct
22 Correct 13 ms 324 KB Output is correct
23 Correct 13 ms 332 KB Output is correct

Subtask #3
0 / 60.0

# 결과 실행 시간 메모리 Grader output
1 Correct 1 ms 204 KB Output is correct
2 Correct 1 ms 204 KB Output is correct
3 Correct 1 ms 204 KB Output is correct
4 Correct 1 ms 204 KB Output is correct
5 Correct 1 ms 204 KB Output is correct
6 Correct 0 ms 204 KB Output is correct
7 Correct 1 ms 204 KB Output is correct
8 Correct 1 ms 204 KB Output is correct
9 Correct 1 ms 204 KB Output is correct
10 Correct 1 ms 320 KB Output is correct
11 Correct 1 ms 204 KB Output is correct
12 Correct 6 ms 332 KB Output is correct
13 Correct 6 ms 204 KB Output is correct
14 Correct 4 ms 204 KB Output is correct
15 Correct 4 ms 204 KB Output is correct
16 Correct 1 ms 332 KB Output is correct
17 Correct 21 ms 324 KB Output is correct
18 Correct 18 ms 332 KB Output is correct
19 Correct 12 ms 332 KB Output is correct
20 Correct 62 ms 204 KB Output is correct
21 Correct 53 ms 204 KB Output is correct
22 Correct 13 ms 324 KB Output is correct
23 Correct 13 ms 332 KB Output is correct
24 Correct 192 ms 340 KB Output is correct
25 Correct 118 ms 452 KB Output is correct
26 Correct 220 ms 332 KB Output is correct
27 Correct 195 ms 352 KB Output is correct
28 Correct 222 ms 332 KB Output is correct
29 Correct 111 ms 316 KB Output is correct
30 Correct 131 ms 332 KB Output is correct
31 Correct 1 ms 332 KB Output is correct
32 Correct 1 ms 332 KB Output is correct
33 Execution timed out 1082 ms 332 KB Time limit exceeded
34 Halted 0 ms 0 KB -