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計算幾何(point&line)紅書模板

const int MAXN = 1e6 + 5;
const double eps = 1e-8;

int cmp(double x) {
    if(fabs(x) < eps) return 0;
    if(x > 0) return 1;
    return -1;
}

const double pi = acos(-1.0);
inline double sqr(double x) {
    return x * x;
}
struct point{
    double x, y;
    point(){}
    point(double a, double
b) : x(a), y(b) {} void input() { scanf("%lf%lf", &x, &y); } friend point operator + (const point &a, const point &b) { return point(a.x + b.x, a.y + b.y); } friend point operator - (const point &a, const point &b) { return point(a.x - b.x, a.y - b.y); } friend
bool operator == (const point &a, const point &b) { return cmp(a.x - b.x) == 0 && cmp(a.y - b.y) == 0; } friend point operator * (const point &a, const double &b) { return point(a.x * b, a.y * b); } friend point operator * (const double &a, const
point &b) { return point(a * b.x, a * b.y); } friend point operator / (const point &a, const double &b) { return point(a.x / b, a.y / b); } double norm() { return sqrt(sqr(x) + sqr(y)); } }; double det(const point &a, const point &b) { return a.x * b.y - a.y * b.x; } double dot(const point &a, const point &b) { return a.x * b.x + a.y * b.y; } double dist(const point &a, const point &b) { return (a - b).norm(); } point rotate_point(const point &p, double A) { double tx = p.x, ty = p.y; return point(tx * cos(A) - ty * sin(A), tx * sin(A) + ty * cos(A)); } struct line{ point a, b; line(){} line(point x, point y) : a(x), b(y){} }; line point_make_line(const point a, const point b) { return line(a, b); } double dis_point_segment(const point p, const point s, const point t) { if(cmp(dot(p-s, t-s)) < 0) return (p - s).norm(); if(cmp(dot(p-t, s-t)) < 0) return (p - t).norm(); return fabs(det(s-p, t-p)/dist(s,t)); } void PointProjLine(const point p,const point s, const point t,point &cp){ double r = dot((t-s), (p-s))/dot(t-s, t-s); cp=s+r*(t-s); } bool PointOnSegment(point p, point s, point t){ return cmp(det(p-s, t-s))==0 && cmp(dot(p-s,p-t))<=0; } bool parallel(line a,line b){ return !cmp(det(a.a-a.b,b.a-b.b)); } bool line_make_point(line a,line b,point &res){ if (parallel(a,b)) return false; double s1=det(a.a-b.a,b.b-b.a); double s2=det(a.b-b.a,b.b-b.a); res=(s1*a.b-s2*a.a)/(s1-s2); return true; } line move_d(line a, const double &len) { point d = a.b - a.a; d = d / d.norm(); d = rotate_point(d, pi/2); return line(a.a + d*len, a.b + d * len); }