Tiger in the Woods (Issue 12, p46) - Glitches

Poor old issue 12 has some further glitches, it seems - I have today discovered that 3 of the 6 Tiger in the Woods puzzles on p46 have 2 distinct solutions. Note that these puzzles were not created by Gareth, so it's not his fault!

I discovered this by accident, having never seen this type of puzzle before today, but prompted by Nikki's cry for help on the subject, I decided to have a go. My bumbling efforts to establish a "methodology" resulted in solutions to the first two (6x6) puzzles. Quite by chance I looked in the answers section (I rarely do this), and saw that my solution to the second 6x6 puzzle was not the same as the one given.

After double-checking my solution, I thought I would would knock up a program that could find all solutions to a given TW puzzle. Having got this working, I checked all 7 puzzles on p46 and p47. The results are:

• 6x6 puzzles: #2 and #3 both have two solutions
  
  .
• 9x9 puzzles: #2 has two solutions

The other three on p46, and the one on p47, are all OK.

Since it took me most of the day to get this program up and running, you could say I have got my money's worth out of these puzzles!


The alternate solutions are given below. I give just the start and end-points, and those turning-points where there is a choice of direction. Note that
"left" and "right" are directions as they would apply to a person actually walking the path.

• 6x6 #2
  
  Start at (4,3) heading South, turn left at (5,3) ... left at (2,4), right at (2,3) ... ending at (4,5)
  
  .
• 6x6 #3
  
  Start at (4,4) heading North, turn right at (2,4) ... left at (2,6) ... right at (3,2) ... ending at (4,3)
  
  .
• 9x9 #2
  
  Start at (5,6) heading North, turn left at (4,6), left at (4,4), left at (9,4) ... left at (7,6), right at (7,2) ... ending at (10,3)

Hi Mathimagics,

Upon speaking with Deb Mohanty regarding your comments, we realized that the rules as given in issue 12 were not explicit enough. These are the amendments we plan to add based on Deb's intended rules for the puzzle:

• The line may not cross itself on the starting or ending square.
• The line only comes to a stop when reaching the a black square or the edge of the grid. A valid solution may not stop mid-travel.

Following these rules, the puzzles should only be solvable with the solutions given in the back of the magazine.

We're extremely sorry for not being explicit in the instructions for this puzzle. As with the instructions in the Chess Sum Sudoku puzzle, I will do my best in future issues to make sure that instructions for all puzzle types in the community section are detailed and correct.

OK, no problem in that case.

The first of those additional rules is one that is almost implicit, but could certainly use some clarification.

The second one, regarding the endpoint, certainly solves the uniqueness problems!