The Chifu-chemulpo Puzzle
(
MISCELLANEOUS PUZZLES)
Here is a puzzle that was once on sale in the London shops. It represents a military train—an engine and eight cars. The puzzle is to reverse the cars, so that they shall be in the order 8, 7, 6, 5, 4, 3, 2, 1, instead of 1, 2, 3, 4, 5, 6, 7, 8, with the engine left, as at first, on the side track. Do this in the fewest possible moves. Every time the engine or a car is moved from the main to the side track, or vice versa, it counts a move for each car or engine passed over one of the points. Moves along the main track are not counted. With 8 at the extremity, as shown, there is just room to pass 7 on to the side track, run 8 up to 6, and bring down 7 again; or you can put as many as five cars, or four and the engine, on the siding at the same time. The cars move without the aid of the engine. The purchaser is invited to "try to do it in 20 moves." How many do you require?
Answer:
The solution is as follows. You may accept the invitation to "try to do it in twenty moves," but you will never succeed in performing the feat. The fewest possible moves are twenty-six. Play the cars so as to reach the following positions:—
E5678 |
———— |
= 10 moves. |
1234 |
E56 |
———— |
= 2 moves. |
123 87 4 |
56 |
———— |
= 5 moves. |
E312 87 4 |
E |
———— |
= 9 moves. |
87654321 |
Twenty-six moves in all.
