MathDB
3 cups with 3 interger units of gallium

Source: 11th QEDMO p10 Seniors (6-8. 12. 2012) https://artofproblemsolving.com/community/c1512515_qedmo_200507

May 16, 2021
combinatorics

Problem Statement

Let there be three cups A,BA, B and CC, which start with a,ba, b and cc (all of them are natural numbers) units of gallium filled. It is also believed that all cups are large enough to contain the total amount of gallium available. It is now allowed to move gallium from one cup to another cup, provided that the contents of the latter cup are exactly double. (a) For which starting positions is it possible to empty one of the cups? (b) For which starting positions is it possible to put all of the gallium in one cup?