#include<bits/stdc++.h>using namespace std;const double eps =1e-8;const double INF =1e20;const double pi = acos ;int dcmp (double x) {if (fabs (x) < eps) return0;return (x <0-1:1);》}inline double sqr (double x) {return x*x;}f %.2f\n", x, y);}bool operator== (const Point &b) const {return (dcmp ==0&& dcmp ==0);}bool operator< (const Point &b) const {return (dcmp ==0 dcmp <0: x < ;}；Point operator+ (const Point &b) const {return Point (x+, y+;}Point operator- (const Point &b) const {return Point , ;}Point operator* (double a) {return Point (x*a, y*a);}Point operator/ (double a) {`return Point (x/a, y/a);}double len2 () {f\n", r);}bool operator== (const Circle &a) const {return p ==&& (dcmp ==0);}double area () {otate_left ());Line v = Line ((b+c)/2, ((b+c)/2) + (c-b).rotate_left ()); Point p = line_intersection (u, v);]double r = dis (p, a);return Circle (p, r);}Circle in_circle (Point a, Point b, Point c) { r -l*l);Point tmp =+ (l);p1 = tmp + ( ().change_len (h));p2 = tmp + ( ().change_len (h));if (rel ==2|| rel ==4) return1;return2;~}int line_cirlce_intersection (Line v, Circle u, Point &p1, Point &p2) {hange_len (r1));= q + ( ().change_len (r1));== r1;return2;}Line u1 = Line + ().change_len (r1), + ().change_len (r1)); Line u2 = Line + ().change_len (r1), + ().change_len (r1)); Circle cc = Circle (q, r1);.Point p1, p2;if (!line_cirlce_intersection (u1, cc, p1, p2))line_cirlce_intersection (u2, cc, p1, p2);c1 = Circle (p1, r1);if (p1 == p2) {c2 = c1;return1;}c2 = Circle (p2, r1);return2;、}int get_circle (Line u, Line v, double r1, Circle &c1, Circle &c2, Circle &c3, Circle &c4) {hange_len (r1), + ().change_len (r1));Line u2 = Line + ().change_len (r1), + ().change_len (r1)); Line v1 = Line + ().change_len (r1), + ().change_len (r1)); Line v2 = Line + ().change_len (r1), + ().change_len (r1));==== r1;= line_intersection (u1, v1);= line_intersection (u1, v2);= line_intersection (u2, v1);#= line_intersection (u2, v2);return4;}int get_circle (Circle cx, Circle cy, double r1, Circle &c1, Circle &c2) {otate_left ());v = u;return1;}double d = dis , q);double l =*d;。

double h = sqrt *- l*l);u = Line (q, + .change_len (l) + .rotate_left ().change_len (h)); v = Line (q, + .change_len (l) + .rotate_right ().change_len (h));return2;}double area_circle (Circle a, Circle v) {" << endl;return res;}-- ;int d2 = dcmp (b[(i+1)%n].y - ;if (k >0&& d1 <=0&& d2 >0)w++;if (k <0&& d2 <=0&& d1 >0)w--;}if (w !=0)return1;return0;·}int convex_cut (Line u, Point *p, int n, Point *po) {//直线切割多边形左侧//返回切割后多边形的数量int top =0;for (int i =0; i < n; i++) {int d1 = dcmp (cross p[i]);int d2 = dcmp (cross p[(i+1)%n]);if (d1 >=0) po[top++] = p[i];if (d1*d2 <0) po[top++] = line_intersection (u, Line (p[i], p[(i+1)%n]));（}return top;}double convex_circumference (Point *p, int n) {//多边形的周长(凹凸都可以)double ans =0;for (int i =0; i < n; i++) {ans += dis (p[i], p[(i+1)%n]);}return ans;@}double area_polygon_circle (Circle c, Point *p, int n) {//多边形和圆交面积double ans =0;for (int i =0; i < n; i++) {int j = (i+1)%n; //cout << i << " " << j << "//" << endl;if (dcmp (cross (p[j], p[i]) >=0)ans += circle_traingle_area (p[i], p[j], c);elseans -= circle_traingle_area (p[i], p[j], c);、}return fabs (ans);}Point centre_of_gravity (Point *p, int n) {//多边形的重心(凹凸都可以) double sum = , sumx =0, sumy =0;Point p1 = p[0], p2 = p[1], p3;for (int i =2; i <= n-1; i++) {p3 = p[i];double area = cross (p2-p1, p3-p2)/;~sum += area;sumx +=++*area;sumy +=++*area;p2 = p3;}return Point (sumx/*sum), sumy/*sum));}int convex_hull (Point *p, Point *ch, int n) {//求凸包//所有的点集凸包点集点集的点数！sort (p, p+n);int m =0;for (int i =0; i < n; i++) {while (m >1&& cross (ch[m-1]-ch[m-2], p[i]-ch[m-1]) <=0) m--;ch[m++] = p[i];}int k = m;for (int i = n-2; i >=0; i--) {while (m > k && cross (ch[m-1]-ch[m-2], p[i]-ch[m-1]) <=0) m--;ch[m++] = p[i];}if (n >1)m--;return m;}。