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Baltic Way
2016 Baltic Way
14
14
Part of
2016 Baltic Way
Problems
(1)
Combinatorics in a cube
Source: Baltic Way 2016, Problem 14
11/5/2016
A cube consists of
4
3
4^3
4
3
unit cubes each containing an integer. At each move, you choose a unit cube and increase by
1
1
1
all the integers in the neighbouring cubes having a face in common with the chosen cube. Is it possible to reach a position where all the
4
3
4^3
4
3
integers are divisible by
3
,
3,
3
,
no matter what the starting position is?
combinatorics