Poj 2540 & amp; UV 10084 Hotter Colder (semi-flat)

Poj 2540 & amp; ultraviolet A 10084 Hotter Colder (semi-flat)

"Getting cooler and hotter" is a game: two people close their eyes in a square room () and () on the left of the lower-left corner and the upper-right corner, B hid something in the room. Then, you can guess where this item is. The first time you have to guess it is (0, 0 ). The second time I guess a location, I have to answer "Hotter", "Colder", and "Same ".

"Hotter" indicates that the new guess point is closer than the previous one, and "Colder" indicates that the new guess point is farther than the previous one, "Same" indicates that the two guesses are as close as possible. The answer to location B of each guess is given in order. Output the total area of all possible locations after each answer.

Idea: For two vertices A and B. If the distance between P and a is less than the distance from B, P must be on the vertical line of A and B near the side of A, and vice versa. If the distance between P and A and B is equal, P must be on the center vertical line of A and B. It can be imagined that each answer is equivalent to a cut on the polygon of the answer, that is, the intersection of the polygon and the half plane. Complexity O (n) of each cut)

Code:

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                   using namespace std;#define LL long longconst double eps = 1e-6;const double pi = acos(-1.0);int cmp(double x) { if(fabs(x) < eps) return 0; if(x > 0)return 1; return -1;}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 bool operator < (const point &a, const point& b) { return cmp(a.x - b.x) < 0 || 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();}double Angle(point a, point b) { if(cmp(dot(a, b) - a.norm() * b.norm()) == 0) return 0; if(cmp(dot(a, b) + a.norm() * b.norm()) == 0) return pi; return acos(dot(a,b) / a.norm() / b.norm()); }double angle(point p) { return atan2(p.y, p.x);}point point_rotate(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));}point point_rotate(const point &p, double sint, double cost) { double tx = p.x, ty = p.y; return point(tx * cost - ty * sint, tx * sint + ty * cost);}struct line { point a, b; line(){} line(point x, point y):a(x),b(y){} void input() { a.input(); b.input(); }};void point_pro_line(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 point_pro_segment(const point p, const point s, const point t, point &cp) { if(cmp(dot(p - s, t - s))<0) { cp = s; return 0; } if(cmp(dot(p - t, s - t))<0) { cp = t; return 0; } double r = dot(t - s, p - s) / dot (t - s, t - s); cp = s + r * (t - s); return 1;}bool point_on_segment(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_cross_line(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;}int segment_cross_segment(const point& a1,const point& a2,const point& b1,const point& b2, point& res) { double c1 = det(a2 - a1, b1 - a1); double c2 = det(a2 - a1, b2 - a1); double c3 = det(b2 - b1, a1 - b1); double c4 = det(b2 - b1, a2 - b1); if (cmp(c1) * cmp(c2) < 0 && cmp(c3) * cmp(c4) < 0) { res.x = (b1.x * c2 - b2.x * c1) / (c2 - c1); res.y = (b1.y * c2 - b2.y * c1) / (c2 - c1); return 1; } if(point_on_segment(a1, b1, b2)) { res = a1; return 2; } if(point_on_segment(a2, b1, b2)) { res = a2; return 2; } if(point_on_segment(b1, a1, a2)) { res = b1; return 2; } if(point_on_segment(b2, a1, a2)) { res = b2; return 2; } return 0;}int segment_cross_segment(const line& l1, const line& l2, point& res) { point a1 = l1.a, a2 = l1.b, b1 = l2.a, b2 = l2.b; double c1 = det(a2 - a1, b1 - a1); double c2 = det(a2 - a1, b2 - a1); double c3 = det(b2 - b1, a1 - b1); double c4 = det(b2 - b1, a2 - b1); if (cmp(c1) * cmp(c2) < 0 && cmp(c3) * cmp(c4) < 0) { res.x = (b1.x * c2 - b2.x * c1) / (c2 - c1); res.y = (b1.y * c2 - b2.y * c1) / (c2 - c1); return 1; } if(point_on_segment(a1, b1, b2)) { res = a1; return 2; } if(point_on_segment(a2, b1, b2)) { res = a2; return 2; } if(point_on_segment(b1, a1, a2)) { res = b1; return 2; } if(point_on_segment(b2, a1, a2)) { res = b2; return 2; } return 0;}struct polygon { vector
                   
                     P; polygon(int size = 0) { P.resize(size); } point& operator [](int index) { return P[index]; } int size() { return P.size(); } double area() { int n = size(); double sum = 0; for(int i = 0; i < n; i++) sum += det(P[i], P[(i + 1) % n]); return sum * 0.5; }};polygon polygon_cut(polygon& pol, const point& a, const point& b) { int n = pol.size(); point c, d, p; polygon ret; for(int i = 0; i < n; i++) { c = pol[i]; d = pol[(i + 1) % n]; if(cmp(det(b - a, c - a)) >= 0) ret.P.push_back(c); if(line_cross_line(line(a, b), line(c, d), p)) { if(point_on_segment(p, c, d)) ret.P.push_back(p); } } return ret;}int main() { polygon pol(4); pol[0] = point(0, 0); pol[1] = point(10, 0); pol[2] = point(10, 10); pol[3] = point(0, 10); point p, q = point(0, 0); char str[10]; bool flag = 0; while(scanf("%lf%lf%s", &p.x, &p.y, str) != EOF) { point a = (p + q) / 2; point b = point_rotate(p - q, pi * 0.5) + a; if(str[0] == 'S') flag = 1; if(flag) { puts("0.00"); continue; } if(str[0] == 'C') { pol = polygon_cut(pol, a, b); } else { pol = polygon_cut(pol, b, a); } printf("%.2f\n", fabs(pol.area())); q = p; } return 0;}