December Problems of the Month Posted on December 8th, 2018 by

Congratulations to November’s successful solvers: Filip Belik, Sam Thompson, and James Wittrig.

December’s Problem #1 is a slippery, sliding rearrangement problem:

Each move in the game below consists of sliding two checkers from adjacent boxes to two open positions, keeping them adjacent and in their original order as they move. In three moves, the pattern is changed from sorted colors to alternating colors:

Following the same rules, change these eight checkers to alternating colors, with no gaps between them, in four moves:

See the complete set of all three problems here: December 2018 Problems of the Month [PDF]

The fine print: Solutions are welcome from all Gustavus students, faculty and staff. Each month’s solvers will be announced along with a running scoreboard for the Fall Series. Prizes of $125 (first place) and $50 (runner up) will be awarded to the top student solvers at the end of the Fall Series; students who have solved at least three problems during the Fall Series are eligible for the prizes. To submit your solutions:

Email solutions to, or
Submit written solutions to Professor Siehler’s mailbox (Olin Hall 310) by December 20th, 2018.

Happy solving!


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