MathDB

5

Part of 2013 South africa National Olympiad

Problems(1)

Neighbouring coins on a chess board

Source: SAMO Senior Round 3 2013 Problem 5

9/17/2013
Some coins are placed on a 20×1320 \times 13 board. Two coins are called neighbours if they are in the same row or column and no other coins lie between them. What is the largest number of coins that can be placed on the board if no coin is allowed to have more than two neighbours?
combinatorics unsolvedcombinatorics