Wednesday, 23 May 2012

No Number Practise: Black and White Matchmaker

This weekend is the No Numbers test at Logic Masters India. It is written by Ko Okamato (Xevs). It contains  only puzzles without numbers in the grid, Most types are new to everyone, although I have come across Synchronised Maze before. It might not be my best performance as some of the types are a bit prone to error. The 2 "No numbers" puzzles have to be approached very carefully as it's easy to accidentally leave a number in when you make a small transcription (No Numbers Field) or reading (No Numbers Loop) error. Prasanna created practise puzzles for the other puzzle types, which can be found here, here and here.

I decided to make a Black and White Matchmaker as practise. I've never been any good at these matchmaker type puzzles. I tend to just avoid them unless it's the only one left. In this test it's over a quarter of the points, so probably wise to attempt. Also it contains the most familiar puzzle types. So I figured it would be worth a try to design one so I could find some easy ways to exclude certain types from certain puzzle grids. I've put in a few of ways I found in the grids. The puzzle turned out okay, but with a bit more effort I could have probably made the puzzles overlap in a few more genres.

I've put all puzzles in a single image with a table to match the puzzle types. I also have all puzzle grids as a seperate image. If it would be preferred that I post them all seperately, I can do that as well.

General Rule

There are 6 puzzle grids given with black and white circles and 5 puzzle types. Match each type to one puzzle grid and solve it under that rule. One of the grids won't be used. Certain grids might be solvable under multiple rules, but it's only possible to match them in one way so all 5 rules can be solved in a seperate grid.

Puzzle Types

Draw a single loop that runs horizontally and vertically though every cell with a circle. In cells with black circles, the loop must make a 90-degree turn and go straight in both neighboring cells. In cells with white circles, the loop must go straight and makes a 90-degree turn in at least one of neighboring cells.

Black & White:
Fill the grid with black or white circles so that all of the circles with same color will be connected vertically or horizontally. Circles with same color can't form a 2x2 square.

Sun & Moon:
Draw a single loop that runs horizontally and vertically through every cell in the grid once. The loop can't make turns between cells with circles of the same color, and makes just one 90-degree turn between cells with circles of different colors.

Not alone:
Fill the grid with black or white circles so that each row or column has the same amount of black circles and white circles. One circle of a color can't be sandwiched by circles of the other color horizontally or vertically.
An array of two or more circles of a same color may be sandwiched by circles of the other color  horizontally or vertically.

Signal loop:
Draw a single loop that runs horizontally and vertically through every cell except cells with black circles. The loop goes straight in cells with white circles.

Click to enlarge


  1. Excellent puzzles. It helped out lot. I also made a matchmaker but definitely of smaller size and easy difficulty level.

  2. Lovely set of puzzles. I was doubting a unique solution near the end, but all worked out well. Great work!

  3. Excellent set. I feel so much more comfortable with Matchmakers now :-)