The file attached with this problem contains a list having lines. Eight numbers are written in each line, which correspond to a quadrilateral whose vertices have coordinates (in Cartesian plane). There are quadrilaterals in this list which are concave.
Details and Assumptions:
As an explicit example, suppose the list had lines, and the following numbers were written on those two lines: We have two quadrilaterals, the first one having its vertices at points and the second one having its vertices at points Your job is to find out how many of them are concave.
Link to the file: http://pastebin.ca/2679837.
If one of the vertices lies on the line joining two other vertices, consider the resulting figure as convex.
This is a computer science problem, and is inspired from ProjectEuler (I don't remember the problem number at the moment).