October 2020
Problem of the Month

Hiroimono
by R. Wayne Schittberger

This Japanese puzzle genre, also known as Goishi Hiroi, dates back at least as far as the 14th century.

The goal is simple: Given an arrangement of stones on the intersections of a grid, remove all the stones according to a strict set of rules.

The first stone to be removed is marked with the number 1.

From the starting stone, you may travel along any grid line to the first stone encountered, which is then removed.

After that, you may continue in the same direction or turn left or right, but you may not reverse direction.

Each time you remove a stone, write a number in the circle as a reminder that the stone now represents an empty intersection.

Here are two examples along with their solutions:

First Example:



Second Example:

Now see if you can solve five of the following puzzles (extra credit for all six).

#1


#2


#3


#4


#5


#6

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Click here for a printer version

Solution to the Problem:

#1


#2


#3


#4


#5 (2 possible positions for #7 - 12)


#6 (2 possible positions for #3 - 16)

Correctly solved by:

1. Colin (Yowie) Bowey ***	Beechworth, Victoria, Australia
2. Ivy Joseph ***	Pune, Maharashtra, India
3. Kelly Stubblefield ***	Mobile, Alabama
4. Katherine Grossman ***	Redlands Middle School, Grand Junction, Colorado
5. Taylor Balding ***	Redlands Middle School, Grand Junction, Colorado

*** Extra credit for solving all six puzzles

Send any comments or questions to: David Pleacher