Let n ≥ 4 is an integer. Suppose that some unit squares of n × n grid are marked. We say that two distinct marked unit squares are line related if they are on the same line and there is no any other marked unit square on the same line located between them. We say that two distinct marked unit squares are column related if they are on the same column and there is no any other marked unit square on the same column located between them. We say that two marked unit squares are related if they are line or column related. Find the maximal possible number of marked unit squares on the n × n grid if any marked unit square is related with an odd number of marked unit squares.
Correct Solutions by,
- Toshihiro Shimizu Kawasaki, Japan
- Murat Beşli Politecnico di Torino, Italy
- Magnus Jakobsson Lund, Sweden
- Roger Bengtsson Lund, Sweden
- Arda Karahan Trabzon Fen Lisesi
- Burak İşiner Eker Bilkent University
- Tamer Türkoğlu
- Mümtaz Ulaş Keskin
- Ramazan Karaşahin Ankara
- Choi Min Kyu South Korea
Solution 2506a.pdf (bilkent.edu.tr)