From 21d8d8f405048b1d9e4597f0f6fabc45ffdff20f Mon Sep 17 00:00:00 2001 From: kittobi1992 Date: Sat, 22 Nov 2014 16:57:15 +0100 Subject: wrong --- geometry/convexHull | 49 ------------------------------------------------- 1 file changed, 49 deletions(-) delete mode 100644 geometry/convexHull (limited to 'geometry') diff --git a/geometry/convexHull b/geometry/convexHull deleted file mode 100644 index 5d6bc16..0000000 --- a/geometry/convexHull +++ /dev/null @@ -1,49 +0,0 @@ -#include -#include -#include -#include -#include -using namespace std; - -struct point { - double x, y; - point(){} point(double x, double y) : x(x), y(y) {} - bool operator <(const point &p) const { - return x < p.x || (x == p.x && y < p.y); - } -}; - -// 2D cross product. -// Return a positive value, if OAB makes a counter-clockwise turn, -// negative for clockwise turn, and zero if the points are collinear. -double cross(const point &O, const point &A, const point &B){ - double d = (A.x - O.x) * (B.y - O.y) - (A.y - O.y) * (B.x - O.x); - if (fabs(d) < 1e-9) return 0.0; - return d; -} - -// Returns a list of points on the convex hull in counter-clockwise order. -// Colinear points are not in the convex hull, if you want colinear points in the hull remove "=" in the CCW-Test -// Note: the last point in the returned list is the same as the first one. -vector convexHull(vector P){ - int n = P.size(), k = 0; - vector H(2*n); - - // Sort points lexicographically - sort(P.begin(), P.end()); - - // Build lower hull - for (int i = 0; i < n; i++) { - while (k >= 2 && cross(H[k-2], H[k-1], P[i]) <= 0.0) k--; - H[k++] = P[i]; - } - - // Build upper hull - for (int i = n-2, t = k+1; i >= 0; i--) { - while (k >= t && cross(H[k-2], H[k-1], P[i]) <= 0.0) k--; - H[k++] = P[i]; - } - - H.resize(k); - return H; -} -- cgit v1.2.3