MathDB
Counting cards

Source: Tournament of Towns,Spring 2002, Senior A Level, P6

May 14, 2014
combinatorics proposedcombinatorics

Problem Statement

The 5252 cards of a standard deck are placed in a 13×413\times 4 array. If every two adjacent cards, vertically or horizontally, have the same suit or have the same value, prove that all 1313 cards of the same suit are in the same row.