Dagens rekursion

Algorithm INTERSECTHALFPLANES(H)
Input. A set H of n half-planes in the plane.
Output. The convex polygonal region C := ⋂ h∈H h.
1.  if card(H) = 1
2.    then C ← the unique half-plane h ∈ H
3.    else Split H into sets H1 and H2 of size n/2 and n/2 .
4.      C1 ← INTERSECTHALFPLANES(H1)
5.      C2 ← INTERSECTHALFPLANES(H2)
6.      C ← INTERSECTCONVEXREGIONS(C1,C2)