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| #include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <algorithm>
#include <sstream>
#include <map>
#include <set>
#include <cmath>
#include <queue>
#define REP(i,k,n) for(int i=k;i<n;i++)
#define rep(i,n) for(int i=0;i<n;i++)
#define INF 1<<30
#define pb push_back
#define mp make_pair
#define EPS 1e-8
#define equals(a,b) fabs((a) - (b)) < EPS
using namespace std;
typedef long long ll;
typedef pair<int,int> P;
struct Point {
double x, y;
Point(double x=0, double y=0) : x(x), y(y) {}
Point operator+(const Point &o) const { return Point(x+o.x, y+o.y); }
Point operator-(const Point &o) const { return Point(x-o.x, y-o.y); }
Point operator*(const double m) const { return Point(x*m, y*m); }
Point operator/(const double d) const { return Point(x/d, y/d); }
bool operator<(const Point &o) const { return x != o.x ? x < o.x : y < o.y; }
bool operator==(const Point &o) const { return fabs(x-o.x) < EPS && fabs(y-o.y) < EPS; }
double cross(const Point &o) const { return x * o.y - y * o.x; }
double dot(const Point &o) const { return x * o.x + y * o.y; }
double atan() const { return atan2(y, x); }
double norm() const { return sqrt(dot(*this)); }
double distance(const Point &o) const { return (o - (*this)).norm(); }
double area(const Point &a,const Point &b) {
Point p = a - (*this), p2 = b - (*this);
return p.cross(p2);
}
double area_abs(const Point &a,const Point &b) const {
Point p = a - (*this), p2 = b - (*this);
return fabs(p.cross(p2)) / 2.0;
}
//線分abが自身に含まれているのかどうか判断する
int between(const Point &a,const Point &b) {
if(area(a,b) != 0) return 0;
if(a.x != b.x) return ((a.x <= x) && (x <= b.x) || (a.x >= x) && (x >= b.x));
else return ((a.y <= y) && (y <= b.y) || (a.y >= y) && (y >= b.y));
}
double distance_seg(const Point& a,const Point& b) {
if((b-a).dot(*this-a) < EPS) {
return (*this-a).norm();
}
if((a-b).dot(*this-b) < EPS) {
return (*this-b).norm();
}
return abs((b-a).cross(*this-a)) / (b-a).norm();
}
bool hitPolygon(const Point& a,const Point& b,const Point& c) {
double t = (b-a).cross(*this-b);
double t2 = (c-b).cross(*this-c);
double t3 = (a-c).cross(*this-a);
if((t > 0 && t2 > 0 && t3 > 0) || ( t < 0 && t2 < 0 && t3 < 0)) {
return true;
}
return false;
}
};
struct Seg {
Point a,b;
Seg (Point a, Point b) : a(a),b(b) {}
bool isOrthogonal(Seg &s) { return equals((b - a).dot(s.b - s.a),0.0); }
bool isParallel(Seg &s) { return equals((b-a).cross(s.b - s.a),0.0); }
bool isIntersect(Seg &s) {
if(s.a.between(a,b) || s.b.between(a,b) || a.between(s.a,s.b) || b.between(s.a,s.b)) {
return true;
}
return ((a-b).cross(s.a-a) * (a-b).cross(s.b-a) < EPS) && ((s.b-s.a).cross(a-s.a)*(s.b-s.a).cross(b-s.a) < EPS);
}
bool distance(Seg &s) {
if((*this).isIntersect(s)) return 0.0;
return min(min(a.distance_seg(s.a,s.b),b.distance_seg(s.a,s.b)),min(s.a.distance_seg(a,b),s.b.distance_seg(a,b)));
}
Point getCrossPoint(Seg &s) {
Point p = s.b - s.a;
double d = abs(p.cross(a-s.a));
double d2 = abs(p.cross(b-s.a));
double t = d / (d+d2);
return a + (b-a)*t;
}
bool operator<(const Seg &o) const {
return a == o.a ? a < o.a : b < o.b;
}
void print() {
cout << "(" << a.x << "," << a.y << ") (" << b.x << "," << b.y << ")" << endl;
}
};
int main() {
int n;
cin >> n;
vector<Seg> segs;
vector<Point> v;
rep(i,n) {
double a,b,c,d;
cin >> a >> b >> c >> d;
Point p1(a,b);
Point p2(c,d);
v.push_back(p1);
v.push_back(p2);
segs.push_back(Seg(p1,p2));
}
int ans = 0;
rep(i,v.size()) {
rep(j,v.size()) {
if(i == j) continue;
Point a = (v[i] - v[j]) * 500;
Point b = (v[j] - v[i]) * 500;
Seg seg(v[i]+a,v[j]+b);
int cnt = 0;
rep(k,segs.size()) {
if(seg.isIntersect(segs[k])) {
cnt++;
}
}
ans = max(ans,cnt);
}
}
cout << ans << endl;
return 0;
}
|
