## Sunday, 22 June 2014

This is the next part of my Radar tutorial.
The description of first trick, and the solution of example puzzle has already posted.

Now let's see the second trick, and a new practise puzzle.

If there are a 2 and 3 clue next to each other there is no rectangle that can part of both rows.
Similarly if there are a 3 and 4 clue next to each other there is no rectangle that can part of both rows.

Because of every rectangle is at least 2 units wide. If a clue is 2 then there is only one 2-wide rectangle in that row. Similarly if a clue is 3 then there is only one rectangle in the corresponding row.
So a 2-wide and a 3-wide rectangle cannot be same.

Similarly a 4 clue can be a simple 4 or 2+2. It cannot part a 3-wide rectangle.

First I check if there is anywhere these kind of clues and I draw a bolded line between the two rows. It is a wall. These walls divide the grid into subregions.

In the next practise puzzle it is needed to use this trick and the previous one, too.
The biggest number is 9 in a 12x12 grid. There are 3 empty squares in that row, which seems too many.
But for instance there is a wall between R3 and R4.And it means that R3C7 or R4C7 is empty or both of them. These walls make it possible for the puzzlemaker to use a bit smaller numbers for starting.

Next time I will show the solving steps of this puzzle.