Maths Olympiad Prep

Library / KöMaL problem A /38 of 136

KöMaL problem A, 2016

Combinatorics Difficulty 6.0 National Olympiad Find the answer Hungary

There are given two positive integers: kk and ℓ\ell. A square with horizontal and vertical sides is divided into finitely many rectangles by line segments such that the following statements are satisfied: (i)(i) every horizontal or vertical line of the plane contains at most one of the segments; (ii)(ii) no two segments cross each other in their interiors; (iii)(iii) every horizontal line, intersecting the square but not containing any of the segments, intersects exactly kk rectangles; (iv)(iv) every vertical line, intersecting the square but not containing any of the segments, intersects exactly ℓ\ell rectangles. What can be the number of rectangles?
Russian problem
(5 pont)

We don't reproduce this publisher's solutions. Their own solution is here — work the problem first.
Want a route through all this instead of an archive? The track puts 2,604 problems in a working order, from Junior Challenge level to the IMO shortlist.

Source: KöMaL, licensed Rights held by KöMaL and the MATFUND Foundation. Statement reproduced verbatim; metadata (topic, difficulty) added by this project. Solutions are the publisher's, linked not copied.