Problem

Source: St. Peterwbug MO 2001, 11th grade, P7

Tags: combinatorics, Tiling, Coloring, Rectangles, dominos



Rectangles 1×20, 1×19, ..., 1×1 were cut out of 20×20 table. Prove that the maximal amount of 1×2 dominos can be cut from the table is 85 Proposed by S. Berlov