题目链接:uva 11178 - Morley's Theorem
直接按照题意处理。
<span style="font-size:18px;">#include <cstdio> #include <cstring> #include <cmath> #include <algorithm> using namespace std; const double pi = 4 * atan(1); const double eps = 1e-9; inline int dcmp (double x) { if (fabs(x) < eps) return 0; else return x < 0 ? -1 : 1; } inline double getDistance (double x, double y) { return sqrt(x * x + y * y); } struct Point { double x, y; Point (double x = 0, double y = 0): x(x), y(y) {} void read () { scanf("%lf%lf", &x, &y); } void write () { printf("%lf %lf", x, y); } bool operator == (const Point& u) const { return dcmp(x - u.x) == 0 && dcmp(y - u.y) == 0; } bool operator != (const Point& u) const { return !(*this == u); } bool operator < (const Point& u) const { return x < u.x || (x == u.x && y < u.y); } bool operator > (const Point& u) const { return u < *this; } bool operator <= (const Point& u) const { return *this < u || *this == u; } bool operator >= (const Point& u) const { return *this > u || *this == u; } Point operator + (const Point& u) { return Point(x + u.x, y + u.y); } Point operator - (const Point& u) { return Point(x - u.x, y - u.y); } Point operator * (const double u) { return Point(x * u, y * u); } Point operator / (const double u) { return Point(x / u, y / u); } }; typedef Point Vector; struct Line { double a, b, c; Line (double a = 0, double b = 0, double c = 0): a(a), b(b), c(c) {} }; namespace Punctual { double getDistance (Point a, Point b) { double x=a.x-b.x, y=a.y-b.y; return sqrt(x*x + y*y); } }; namespace Vectorial { /* 点积: 两向量长度的乘积再乘上它们夹角的余弦, 夹角大于90度时点积为负 */ double getDot (Vector a, Vector b) { return a.x * b.x + a.y * b.y; } /* 叉积: 叉积等于两向量组成的三角形有向面积的两倍, cross(v, w) = -cross(w, v) */ double getCross (Vector a, Vector b) { return a.x * b.y - a.y * b.x; } double getLength (Vector a) { return sqrt(getDot(a, a)); } double getAngle (Vector u) { return atan2(u.y, u.x); } double getAngle (Vector a, Vector b) { return acos(getDot(a, b) / getLength(a) / getLength(b)); } /* 正数逆时针 */ Vector rotate (Vector a, double rad) { return Vector(a.x*cos(rad)-a.y*sin(rad), a.x*sin(rad)+a.y*cos(rad)); } /* 单位法线 */ Vector getNormal (Vector a) { double l = getLength(a); return Vector(-a.y/l, a.x/l); } }; namespace Linear { using namespace Vectorial; Line getLine (double x1, double y1, double x2, double y2) { return Line(y2-y1, x1-x2, y1*(x2-x1)-x1*(y2-y1)); } Line getLine (double a, double b, Point u) { return Line(a, -b, u.y * b - u.x * a); } bool getIntersection (Line p, Line q, Point& o) { if (fabs(p.a * q.b - q.a * p.b) < eps) return false; o.x = (q.c * p.b - p.c * q.b) / (p.a * q.b - q.a * p.b); o.y = (q.c * p.a - p.c * q.a) / (p.b * q.a - q.b * p.a); return true; } /* 直线pv和直线qw的交点 */ bool getIntersection (Point p, Vector v, Point q, Vector w, Point& o) { if (dcmp(getCross(v, w)) == 0) return false; Vector u = p - q; double k = getCross(w, u) / getCross(v, w); o = p + v * k; return true; } /* 点p到直线ab的距离 */ double getDistanceToLine (Point p, Point a, Point b) { return fabs(getCross(b-a, p-a) / getLength(b-a)); } double getDistanceToSegment (Point p, Point a, Point b) { if (a == b) return getLength(p-a); Vector v1 = b - a, v2 = p - a, v3 = p - b; if (dcmp(getDot(v1, v2)) < 0) return getLength(v2); else if (dcmp(getDot(v1, v3)) > 0) return getLength(v3); else return fabs(getCross(v1, v2) / getLength(v1)); } /* 点p在直线ab上的投影 */ Point getPointToLine (Point p, Point a, Point b) { Vector v = b-a; return a+v*(getDot(v, p-a) / getDot(v,v)); } /* 判断线段是否存在交点 */ bool haveIntersection (Point a1, Point a2, Point b1, Point b2) { double c1=getCross(a2-a1, b1-a1), c2=getCross(a2-a1, b2-a1), c3=getCross(b2-b1, a1-b1), c4=getCross(b2-b1,a2-b1); return dcmp(c1)*dcmp(c2) < 0 && dcmp(c3)*dcmp(c4) < 0; } /* 判断点是否在线段上 */ bool onSegment (Point p, Point a, Point b) { return dcmp(getCross(a-p, b-p)) == 0 && dcmp(getDot(a-p, b-p)); } } namespace Triangular { using namespace Vectorial; double getAngle (double a, double b, double c) { return acos((a*a+b*b-c*c) / (2*a*b)); } double getArea (double a, double b, double c) { double s =(a+b+c)/2; return sqrt(s*(s-a)*(s-b)*(s-c)); } double getArea (double a, double h) { return a * h / 2; } double getArea (Point a, Point b, Point c) { return fabs(getCross(b - a, c - a)) / 2; } }; namespace Polygonal { using namespace Vectorial; double getArea (Point* p, int n) { double ret = 0; for (int i = 1; i < n-1; i++) ret += getCross(p[i]-p[0], p[i+1]-p[0]); return fabs(ret)/2; } }; using namespace Vectorial; using namespace Linear; Point solve (Point a, Point b, Point c) { double corb = getAngle(a - b, c - b); Vector vb = rotate(c - b, corb/3); double corc = getAngle(a - c, b - c); Vector vc = rotate(b - c, -corc/3); Point o; getIntersection(b, vb, c, vc, o); return o; } int main () { int cas; scanf("%d", &cas); Point a, b, c, d, e, f; while (cas--) { a.read(), b.read(), c.read(); d = solve(a, b, c); e = solve(b, c, a); f = solve(c, a, b); printf("%lf %lf %lf %lf %lf %lf\n", d.x, d.y, e.x, e.y, f.x, f.y); } return 0; } </span>