oj.uz

Submission #448089

# Submission time Handle Problem Language Result Execution time Memory
448089 2021-07-28T20:27:05 Z Antekb Geometrija (COCI21_geometrija) C++14
110 / 110
 396 ms 708 KB 
#include<bits/stdc++.h>
#define st first
#define nd second
using namespace std;
typedef long long ll;
typedef long double ld;

struct pii{
	int x, y;
	pii(int x, int y): x(x), y(y){}
	pii operator -(pii a){return pii(x-a.x, y-a.y);}
	bool operator <(pii a){return (x<a.x || (x==a.x && y<a.y));}
	bool operator ==(pii a){return x==a.x && y==a.y;}
	ld dl(){return sqrt(x*1ll*x+y*1ll*y);}
};
ll cross(pii a, pii b){
	return a.x*1ll*b.y-a.y*1ll*b.x;
}
ll cross(pii a, pii b, pii c){
	return cross(b-a, c-a);
}
int sgn(ll a){
	if(a==0)return 0;
	return a/abs(a);
}
ll dot(pii a, pii b){
	return a.x*1ll*b.x+b.y*1ll*a.y;
}
ll dot(pii a, pii b, pii c){
	return dot(b-a, c-a);
}
typedef pair<pii, pii> odc;
vector<pii> V;
bool check(odc tt){
	vector<ld> A, B;
	for(int i=0; i<V.size(); i++){
		ll t=sgn(cross(tt.st, V[i], tt.nd));
		if(t>0){
			A.push_back(dot(tt.st, tt.nd, V[i])/(V[i]-tt.st).dl());
			B.push_back(dot(tt.nd, tt.st, V[i])/(V[i]-tt.nd).dl());
		}
	}
	sort(A.begin(), A.end());
	sort(B.begin(), B.end());
	//cout<<tt.st.x<<" "<<tt.st.y<<" "<<tt.nd.x<<" "<<tt.nd.y<<"\n";
	//cout<<A.size()<<"\n";
	for(int i=0; i<V.size(); i++){
		ll t=sgn(cross(tt.st, V[i], tt.nd));
		if(t<0){
			ld k=dot(tt.st, tt.nd, V[i])/(V[i]-tt.st).dl(), l=dot(tt.nd, tt.st, V[i])/(V[i]-tt.nd).dl();
			k=-k;
			l=-l;
			if(lower_bound(A.begin(), A.end(), k)-A.begin()+lower_bound(B.begin(), B.end(), l)-B.begin()!=A.size()){
				return 0;
			}
		}
	}
	return 1;
}
pair<vector<pii>, vector<pii> > hull(){
	sort(V.begin(), V.end());
	vector<pii> ans, ans2;
	sort(V.begin()+1, V.end(), [](pii A, pii B){return cross(A-V[0], B-V[0])>0;});
	ans.push_back(V[0]);
	ans.push_back(V[1]);
	//for(int i=0; i<V.size(); i++)cout<<V[i].x<<" "<<V[i].y<<"\n";
	for(int i=2; i<V.size(); i++){
		while(ans.size()>=2 && cross(ans.back(), ans[ans.size()-2], V[i])>0){
			ans2.push_back(ans.back());
			ans.pop_back();
		}
		ans.push_back(V[i]);
	}
	return {ans, ans2};
}
typedef array<pii, 3> tri;
int main(){
	int n;
	cin>>n;
	V.resize(n, pii(0, 0));
	for(pii &i:V){
		cin>>i.x>>i.y;
	}
	auto h=hull();
	assert(h.st.size()>2);
	//cout<<h.st.size();
	vector<tri> tra;
	for(int i=2; i<h.st.size(); i++){
		tra.push_back({h.st[0], h.st[i-1], h.st[i]});
	}
	//cout<<tra.size();
	for(pii i:h.nd){
		bool b=0;
		for(int j=0; j<tra.size(); j++){
			int a1=sgn(cross(i, tra[j][0], tra[j][1])),a2=sgn(cross(i, tra[j][1], tra[j][2])),a3=sgn(cross(i, tra[j][2], tra[j][0]));
			if(a1==a2 && a2==a3){
				b=1;
				tra.push_back({i, tra[j][0], tra[j][1]});
				tra.push_back({i, tra[j][1], tra[j][2]});
				tra.push_back({i, tra[j][2], tra[j][0]});
				swap(tra[j], tra.back());
				tra.pop_back();
				break;
			}
		}
		assert(b==1);
	}
	//cout<<tra.size();
	vector<odc> todo;
	for(auto i:tra){
		todo.push_back({i[0], i[1]});
		todo.push_back({i[1], i[2]});
		todo.push_back({i[2], i[0]});
	}
	for(auto &i:todo){
		if(i.st<i.nd)swap(i.st, i.nd);
	}
	sort(todo.begin(), todo.end(), [](odc a, odc b){return a.st<b.st || (a.st==b.st && a.nd<b.nd);});
	int ans=0;
	for(int i=0; i<todo.size(); i++){
		if(i==0 || !(todo[i].st==todo[i-1].st) || !(todo[i].nd==todo[i-1].nd)){
			//cout<<"a";
			ans+=check(todo[i]);
		}
	}
	cout<<ans;
}

Compilation message

geometrija.cpp: In function 'bool check(odc)':
geometrija.cpp:36:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<pii>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   36 |  for(int i=0; i<V.size(); i++){
      |               ~^~~~~~~~~
geometrija.cpp:47:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<pii>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   47 |  for(int i=0; i<V.size(); i++){
      |               ~^~~~~~~~~
geometrija.cpp:53:96: warning: comparison of integer expressions of different signedness: '__gnu_cxx::__normal_iterator<long double*, std::vector<long double> >::difference_type' {aka 'long int'} and 'std::vector<long double>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   53 |    if(lower_bound(A.begin(), A.end(), k)-A.begin()+lower_bound(B.begin(), B.end(), l)-B.begin()!=A.size()){
      |       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~
geometrija.cpp: In function 'std::pair<std::vector<pii>, std::vector<pii> > hull()':
geometrija.cpp:67:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<pii>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   67 |  for(int i=2; i<V.size(); i++){
      |               ~^~~~~~~~~
geometrija.cpp: In function 'int main()':
geometrija.cpp:88:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<pii>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   88 |  for(int i=2; i<h.st.size(); i++){
      |               ~^~~~~~~~~~~~
geometrija.cpp:94:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::array<pii, 3> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   94 |   for(int j=0; j<tra.size(); j++){
      |                ~^~~~~~~~~~~
geometrija.cpp:120:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<pii, pii> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  120 |  for(int i=0; i<todo.size(); i++){
      |               ~^~~~~~~~~~~~

Subtask #1
20.0 / 20.0

# Verdict Execution time Memory 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 1 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 204 KB Output is correct
11 Correct 1 ms 204 KB Output is correct

Subtask #2
30.0 / 30.0

# Verdict Execution time Memory 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 1 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 204 KB Output is correct
11 Correct 1 ms 204 KB Output is correct
12 Correct 13 ms 364 KB Output is correct
13 Correct 12 ms 364 KB Output is correct
14 Correct 10 ms 360 KB Output is correct
15 Correct 10 ms 340 KB Output is correct
16 Correct 7 ms 328 KB Output is correct
17 Correct 10 ms 364 KB Output is correct
18 Correct 12 ms 460 KB Output is correct
19 Correct 11 ms 332 KB Output is correct
20 Correct 8 ms 332 KB Output is correct
21 Correct 9 ms 332 KB Output is correct
22 Correct 11 ms 332 KB Output is correct
23 Correct 11 ms 332 KB Output is correct

Subtask #3
60.0 / 60.0

# Verdict Execution time Memory 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 1 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 204 KB Output is correct
11 Correct 1 ms 204 KB Output is correct
12 Correct 13 ms 364 KB Output is correct
13 Correct 12 ms 364 KB Output is correct
14 Correct 10 ms 360 KB Output is correct
15 Correct 10 ms 340 KB Output is correct
16 Correct 7 ms 328 KB Output is correct
17 Correct 10 ms 364 KB Output is correct
18 Correct 12 ms 460 KB Output is correct
19 Correct 11 ms 332 KB Output is correct
20 Correct 8 ms 332 KB Output is correct
21 Correct 9 ms 332 KB Output is correct
22 Correct 11 ms 332 KB Output is correct
23 Correct 11 ms 332 KB Output is correct
24 Correct 387 ms 588 KB Output is correct
25 Correct 377 ms 552 KB Output is correct
26 Correct 396 ms 588 KB Output is correct
27 Correct 385 ms 600 KB Output is correct
28 Correct 366 ms 556 KB Output is correct
29 Correct 246 ms 564 KB Output is correct
30 Correct 262 ms 460 KB Output is correct
31 Correct 179 ms 580 KB Output is correct
32 Correct 180 ms 460 KB Output is correct
33 Correct 236 ms 588 KB Output is correct
34 Correct 270 ms 588 KB Output is correct
35 Correct 335 ms 708 KB Output is correct
36 Correct 333 ms 588 KB Output is correct
37 Correct 184 ms 588 KB Output is correct
38 Correct 228 ms 596 KB Output is correct
39 Correct 333 ms 588 KB Output is correct
40 Correct 345 ms 600 KB Output is correct
41 Correct 379 ms 596 KB Output is correct
42 Correct 374 ms 608 KB Output is correct