训练指南267页

#include <iostream>#include <cstdio>#include <cstring>#include <cstdlib>#include <cmath>#include <vector>#include <queue>#include <map>#include <algorithm>#include <set>#define MM(a) memset(a,0,sizeof(a))typedef long long ll;typedef unsigned long long ULL;const double eps = 1e-10;const int inf = 0x3f3f3f3f;using namespace std;

struct Point {    double x, y;    Point() {}    Point(double x, double y) {        this->x = x;        this->y = y;    }    void read() {        scanf("%lf%lf", &x, &y);    }};

typedef Point Vector;

Vector operator + (Vector A, Vector B) {    return Vector(A.x + B.x, A.y + B.y);}

Vector operator - (Vector A, Vector B) {    return Vector(A.x - B.x, A.y - B.y);}

Vector operator * (Vector A, double p) {    return Vector(A.x * p, A.y * p);}

Vector operator / (Vector A, double p) {    return Vector(A.x / p, A.y / p);}

bool operator < (const Point& a, const Point& b) {    return a.x < b.x || (a.x == b.x && a.y < b.y);}const double PI = acos(-1.0);

int dcmp(double x) {    if (fabs(x) < eps) return 0;    else return x < 0 ? -1 : 1;}

bool operator == (const Point& a, const Point& b) {    return dcmp(a.x - b.x) == 0 && dcmp(a.y - b.y) == 0;}

double Dot(Vector A, Vector B) {return A.x * B.x + A.y * B.y;} //点积double Length(Vector A) {return sqrt(Dot(A, A));} //向量的模double Angle(Vector A, Vector B) {return acos(Dot(A, B) / Length(A) / Length(B));} //向量夹角double Cross(Vector A, Vector B) {return A.x * B.y - A.y * B.x;} //叉积double Area2(Point A, Point B, Point C) {return Cross(B - A, C - A);} //有向面积double angle(Vector v) {return atan2(v.y, v.x);}

Point GetLineIntersection(Point P, Vector v, Point Q, Vector w) {    Vector u = P - Q;    double t = Cross(w, u) / Cross(v, w);    return P + v * t;}

Vector Rotate(Vector A, double rad) {    return Vector(A.x * cos(rad) - A.y * sin(rad), A.x * sin(rad) + A.y * cos(rad));}

double DistanceToLine(Point P, Point A, Point B) {    Vector v1 = B - A, v2 = P - A;    return fabs(Cross(v1, v2)) / Length(v1);}

Vector AngleBisector(Point p, Vector v1, Vector v2){//给定两个向量,求角平分线    double rad = Angle(v1, v2);    return Rotate(v1, dcmp(Cross(v1, v2)) * 0.5 * rad);}

//求线与x轴的真实角(0<=X<180)double RealAngleWithX(Vector a){    Vector b(1, 0);    if (dcmp(Cross(a, b)) == 0) return 0.0;    else if (dcmp(Dot(a, b) == 0)) return 90.0;    double rad = Angle(a, b);    rad = (rad / PI) * 180.0;    if (dcmp(a.y) < 0) rad = 180.0 - rad;    return rad;}

struct Circle {    Point c;    double r;    Circle(Point c, double r) {        this->c = c;        this->r = r;    }    Point point(double a) {        return Point(c.x + cos(a) * r, c.y + sin(a) * r);    }};

//求直线与圆的交点int getLineCircleIntersection(Point p, Vector v, Circle c, vector<Point> &sol) {    double a1 = v.x, b1 = p.x - c.c.x, c1 = v.y, d1 = p.y - c.c.y;    double e1 = a1 * a1 +  c1 * c1, f1 = 2 * (a1 * b1 + c1 * d1), g1 = b1 * b1 + d1 * d1 - c.r * c.r;    double delta = f1 * f1 - 4 * e1 * g1, t;    if(dcmp(delta) < 0) return 0;    else if(dcmp(delta) == 0){        t = (-f1) / (2 * e1);        sol.push_back(p + v * t);        return 1;    } else{        t = (-f1 + sqrt(delta)) / (2 * e1); sol.push_back(p + v * t);        t = (-f1 - sqrt(delta)) / (2 * e1); sol.push_back(p + v * t);        return 2;    }}

//两圆相交int getCircleCircleIntersection(Circle C1, Circle C2, vector<Point> &sol) {    double d = Length(C1.c - C2.c);    if (dcmp(d) == 0) {        if (dcmp(C1.r - C2.r) == 0) return -1; // 重合        return 0;    }    if (dcmp(C1.r + C2.r - d) < 0) return 0;    if (dcmp(fabs(C1.r - C2.r) - d) > 0) return 0;    double a = angle(C2.c - C1.c);    double da = acos((C1.r * C1.r + d * d - C2.r * C2.r) / (2 * C1.r * d));    Point p1 = C1.point(a - da), p2 = C1.point(a + da);    sol.push_back(p1);    if(p1 == p2) return 1;    sol.push_back(p2);    return 2;

}

//点到圆的切线int getTangents(Point p, Circle C, Vector *v) {    Vector u = C.c - p;    double dist = Length(u);    if (dist < C.r) return 0;    else if (dcmp(dist - C.r) == 0) {        v[0] = Rotate(u, PI / 2);        return 1;    } else {        double ang = asin(C.r / dist);        v[0] = Rotate(u, -ang);        v[1] = Rotate(u, +ang);        return 2;    }}

//两圆公切线//a[i], b[i]分别是第i条切线在圆A和圆B上的切点int getCircleTangents(Circle A, Circle B, Point *a, Point *b) {    int cnt = 0;    if (A.r < B.r) { swap(A, B); swap(a, b); }    //圆心距的平方    double d2 = (A.c.x - B.c.x) * (A.c.x - B.c.x) + (A.c.y - B.c.y) * (A.c.y - B.c.y);    double rdiff = A.r - B.r;    double rsum = A.r + B.r;    double base = angle(B.c - A.c);    //重合有无限多条    if (d2 == 0 && dcmp(A.r - B.r) == 0) return -1;    //内切    if (dcmp(d2 - rdiff * rdiff) == 0) {        a[cnt] = A.point(base);        b[cnt] = B.point(base);        cnt++;        return 1;    }    //有外公切线    double ang = acos((A.r - B.r) / sqrt(d2));    a[cnt] = A.point(base + ang); b[cnt] = B.point(base + ang); cnt++;    a[cnt] = A.point(base - ang); b[cnt] = B.point(base - ang); cnt++;

    //一条内切线,两条内切线    if (dcmp(d2 - rsum*rsum) == 0) {        a[cnt] = A.point(base); b[cnt] = B.point(PI + base); cnt++;    } else if (dcmp(d2 - rsum*rsum) > 0) {        double ang = acos((A.r + B.r) / sqrt(d2));        a[cnt] = A.point(base + ang); b[cnt] = B.point(base + ang); cnt++;        a[cnt] = A.point(base - ang); b[cnt] = B.point(base - ang); cnt++;    }    return cnt;}

//三角形外切圆Circle CircumscribedCircle(Point p1, Point p2, Point p3) {    double Bx = p2.x - p1.x, By = p2.y - p1.y;    double Cx = p3.x - p1.x, Cy = p3.y - p1.y;    double D = 2 * (Bx * Cy - By * Cx);    double cx = (Cy * (Bx * Bx + By * By) - By * (Cx * Cx + Cy * Cy)) / D + p1.x;    double cy = (Bx * (Cx * Cx + Cy * Cy) - Cx * (Bx * Bx + By * By)) / D + p1.y;    Point p = Point(cx, cy);    return Circle(p, Length(p1 - p));}

//三角形内切圆Circle InscribedCircle(Point p1, Point p2, Point p3) {    double a = Length(p2 - p3);    double b = Length(p3 - p1);    double c = Length(p1 - p2);    Point p = (p1 * a + p2 * b + p3 * c) / (a + b + c);    return Circle(p, DistanceToLine(p, p1, p2));}

//求经过点p1,与直线(p2, w)相切,半径为r的一组圆int CircleThroughAPointAndTangentToALineWithRadius(Point p1, Point p2, Vector w, double r, vector<Point> &sol) {    Circle c1 = Circle(p1, r);    double t = r / Length(w);    Vector u = Vector(-w.y, w.x);    Point p4 = p2 + u * t;    int tot = getLineCircleIntersection(p4, w, c1, sol);    u = Vector(w.y, -w.x);    p4 = p2 + u * t;    tot += getLineCircleIntersection(p4, w, c1, sol);    return tot;}

//给定两个向量,求两向量方向内夹着的圆的圆心。圆与两线均相切,圆的半径已给定Point Centre_CircleTangentTwoNonParallelLineWithRadius(Point p1, Vector v1, Point p2, Vector v2, double r){    Point p0 = GetLineIntersection(p1, v1, p2, v2);    Vector u = AngleBisector(p0, v1, v2);    double rad = 0.5 * Angle(v1, v2);    double l = r / sin(rad);    double t = l / Length(u);    return p0 + u * t;}

//求与两条不平行的直线都相切的4个圆,圆的半径已给定int CircleThroughAPointAndTangentALineWithRadius(Point p1, Vector v1, Point p2, Vector v2, double r, Point *sol) {    int ans = 0;    sol[ans++] = Centre_CircleTangentTwoNonParallelLineWithRadius(p1, v1, p2, v2, r);    sol[ans++] = Centre_CircleTangentTwoNonParallelLineWithRadius(p1, v1 * -1, p2, v2, r);    sol[ans++] = Centre_CircleTangentTwoNonParallelLineWithRadius(p1, v1, p2, v2 * -1, r);    sol[ans++] = Centre_CircleTangentTwoNonParallelLineWithRadius(p1, v1 * -1, p2, v2 * -1, r);    return ans;}

//求与两个相离的圆均外切的一组圆,三种情况int CircleTangentToTwoDisjointCirclesWithRadius(Circle c1, Circle c2, double r, Point *sol){    double dis1 = c1.r + r + r + c2.r;    double dis2= Length(c1.c - c2.c);    if(dcmp(dis1 - dis2) < 0) return 0;    Vector u = c2.c - c1.c;    double t = (r + c1.r) / Length(u);    if(dcmp(dis1 - dis2)==0){        Point p0 = c1.c + u * t;        sol[0] = p0;        return 1;    }    double aa = Length(c1.c - c2.c);    double bb = r + c1.r, cc = r + c2.r;    double rad = acos((aa * aa + bb * bb - cc * cc) / (2 * aa * bb));    Vector w = Rotate(u, rad);    Point p0 = c1.c + w * t;    sol[0] = p0;    w = Rotate(u, -rad);    p0 = c1.c + w * t;    sol[1] = p0;    return 2;}

char op[25];Point p[4];double r[3];

int main() {    while (~scanf("%s", op)) {        if (strcmp(op, "CircumscribedCircle") == 0) {            for (int i = 0; i < 3; i++) p[i].read();            Circle ans = CircumscribedCircle(p[0], p[1], p[2]);            printf("(%.6f,%.6f,%.6f)\n", ans.c.x, ans.c.y, ans.r);        } else if (strcmp(op, "InscribedCircle") == 0) {            for (int i = 0; i < 3; i++) p[i].read();            Circle ans = InscribedCircle(p[0], p[1], p[2]);            printf("(%.6f,%.6f,%.6f)\n", ans.c.x, ans.c.y, ans.r);        } else if (strcmp(op, "TangentLineThroughPoint") == 0) {            p[0].read();            scanf("%lf", &r[0]);            p[1].read();            Vector v[3];            int tot = getTangents(p[1], Circle(p[0], r[0]), v);            double ans[3];            for (int i = 0; i < tot; i++)                ans[i] = RealAngleWithX(v[i]);            sort(ans, ans + tot);            printf("[");            for (int i = 0; i < tot; i++) {                printf("%.6f", ans[i]);                if (i != tot - 1) printf(",");            }            printf("]\n");        } else if (strcmp(op, "CircleThroughAPointAndTangentToALineWithRadius") == 0) {            for (int i = 0; i < 3; i++) p[i].read();            scanf("%lf", &r[0]);            vector<Point> ans;            int tot = CircleThroughAPointAndTangentToALineWithRadius(p[0], p[1], p[2] - p[1], r[0], ans);            sort(ans.begin(), ans.end());            printf("[");            for (int i = 0; i < tot; i++) {                printf("(%.6f,%.6f)", ans[i].x, ans[i].y);                if (i != tot - 1) printf(",");            }            printf("]\n");        } else if (strcmp(op, "CircleTangentToTwoLinesWithRadius") == 0) {            Point ans[4];            for (int i = 0; i < 4; i++) p[i].read();            scanf("%lf", &r[0]);            int tot = CircleThroughAPointAndTangentALineWithRadius(p[0], p[1] - p[0], p[3], p[3] - p[2], r[0], ans);            sort(ans, ans + tot);            printf("[");            for (int i = 0; i < tot; i++) {                printf("(%.6f,%.6f)", ans[i].x, ans[i].y);                if (i != tot - 1) printf(",");            }            printf("]\n");        } else {            p[0].read(); scanf("%lf", &r[0]);            p[1].read(); scanf("%lf", &r[1]);            scanf("%lf", &r[2]);            Point ans[4];            int tot = CircleTangentToTwoDisjointCirclesWithRadius(Circle(p[0], r[0]), Circle(p[1], r[1]), r[2], ans);            sort(ans, ans + tot);            printf("[");            for (int i = 0; i < tot; i++) {                printf("(%.6f,%.6f)", ans[i].x, ans[i].y);                if (i != tot - 1) printf(",");            }            printf("]\n");        }    }    return 0;}

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