The Night Watchman Maze …

I’ve had a couple of email requests about the puzzle in the “Mr. G” post.

I first saw this in a comic book when I was a kid and comic books cost 10-cents/ea. I wasted I don’t know how many hours trying to solve it. Never found a solution until I got to college and used it as a term paper in a logic/math class to answer the question: “Does it have a solution?”

I was successfully able to answer the question and explain my logical solution to get an “A” for the assignment. If you want the answer, request via email and  I’ll reply with the solution. 

I’ve used it in various classrooms when the assigned work is completed in less time than allowed and they need something “fun” to occupy/exercise their curious minds.

The materials required are one personal sized whiteboard and two different color whiteboard markers, one to draw the floor plan the other to draw a path.

As the story goes, a night watchman is assigned the job of locking all the doors of a building for the night. After a few years on the job assigned to the same building, the night watchman is getting a little bored with the job.

He decides to make his job a bit more interesting by trying to see if there is a path through the building where he can lock the all the doors behind him as he passes through each door of the building. The only rule is that he can pass through, close and lock each door once and at the end all the doors must be closed and locked.

He may start inside or outside the building and he can end up either inside or outside the building.

The floor plan of the building is displayed below. It has five rooms and sixteen doorways.Your task is to draw his walking path around and through the building to accomplish his goal.

The building floor plan is easily constructed on a whiteboard.  Starting with a large rectangle, bisect it horizontally in the middle. Then construct the three rooms above the horizontal line and the two large rooms below.  Then erase breaks in each of the walls where indicated to represent the 16 doors.

With practice, it should take less than a minute to draw and easy for the kids to re-construct on their personal whiteboards. 

In any case, it’s not as easy as it looks….