This documentation is automatically generated by online-judge-tools/verification-helper
#include "geometry/convex_polygon_diameter.hpp"
#include "point.hpp"
#include "polygon.hpp"
namespace geometry {
// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_4_B
pair< int, int > convex_polygon_diameter(const Polygon &p) {
int N = (int) p.size();
int is = 0, js = 0;
for(int i = 1; i < N; i++) {
if(imag(p[i]) > imag(p[is])) is = i;
if(imag(p[i]) < imag(p[js])) js = i;
}
Real maxdis = norm(p[is] - p[js]);
int maxi, maxj, i, j;
i = maxi = is;
j = maxj = js;
do {
if(cross(p[(i + 1) % N] - p[i], p[(j + 1) % N] - p[j]) >= 0) {
j = (j + 1) % N;
} else {
i = (i + 1) % N;
}
if(norm(p[i] - p[j]) > maxdis) {
maxdis = norm(p[i] - p[j]);
maxi = i;
maxj = j;
}
} while(i != is || j != js);
return minmax(maxi, maxj);
}
}
#line 2 "geometry/base.hpp"
namespace geometry {
using Real = double;
const Real EPS = 1e-8;
const Real PI = acos(static_cast< Real >(-1));
enum {
OUT, ON, IN
};
inline int sign(const Real &r) {
return r <= -EPS ? -1 : r >= EPS ? 1 : 0;
}
inline bool equals(const Real &a, const Real &b) {
return sign(a - b) == 0;
}
}
#line 3 "geometry/point.hpp"
namespace geometry {
using Point = complex< Real >;
istream &operator>>(istream &is, Point &p) {
Real a, b;
is >> a >> b;
p = Point(a, b);
return is;
}
ostream &operator<<(ostream &os, const Point &p) {
return os << real(p) << " " << imag(p);
}
Point operator*(const Point &p, const Real &d) {
return Point(real(p) * d, imag(p) * d);
}
// rotate point p counterclockwise by theta rad
Point rotate(Real theta, const Point &p) {
return Point(cos(theta) * real(p) - sin(theta) * imag(p), sin(theta) * real(p) + cos(theta) * imag(p));
}
Real cross(const Point &a, const Point &b) {
return real(a) * imag(b) - imag(a) * real(b);
}
Real dot(const Point &a, const Point &b) {
return real(a) * real(b) + imag(a) * imag(b);
}
bool compare_x(const Point &a, const Point &b) {
return equals(real(a), real(b)) ? imag(a) < imag(b) : real(a) < real(b);
}
bool compare_y(const Point &a, const Point &b) {
return equals(imag(a), imag(b)) ? real(a) < real(b) : imag(a) < imag(b);
}
using Points = vector< Point >;
}
#line 2 "geometry/polygon.hpp"
#line 4 "geometry/polygon.hpp"
namespace geometry {
using Polygon = vector< Point >;
using Polygons = vector< Polygon >;
}
#line 3 "geometry/convex_polygon_diameter.hpp"
namespace geometry {
// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=CGL_4_B
pair< int, int > convex_polygon_diameter(const Polygon &p) {
int N = (int) p.size();
int is = 0, js = 0;
for(int i = 1; i < N; i++) {
if(imag(p[i]) > imag(p[is])) is = i;
if(imag(p[i]) < imag(p[js])) js = i;
}
Real maxdis = norm(p[is] - p[js]);
int maxi, maxj, i, j;
i = maxi = is;
j = maxj = js;
do {
if(cross(p[(i + 1) % N] - p[i], p[(j + 1) % N] - p[j]) >= 0) {
j = (j + 1) % N;
} else {
i = (i + 1) % N;
}
if(norm(p[i] - p[j]) > maxdis) {
maxdis = norm(p[i] - p[j]);
maxi = i;
maxj = j;
}
} while(i != is || j != js);
return minmax(maxi, maxj);
}
}