Super unproductive night

Logic Level 5

Above is a Cross the Streams puzzle.

Shade some of the cells black so that all black cells are connected and no $2\times2$ square is entirely shaded black. The clues outside the grid gives the contents of the corresponding row/column, reading from left to right and from top to bottom.

Notations :

A number means a group of consecutive black cells; two different groups in the same row/column must be separated by at least one white cell.
A question mark (?) indicates a single group of unknown size.
an asterisk (*) indicates an unknown number of groups (which may differ in size, and there might be no group at all).

Complete the puzzle and submit your answer as the number black cells used in the $3^\text{rd}$ row plus the number of black cells used in the $8^\text{th}$ row.

Image Credit: Paw-Crafted Logic Puzzles . No copyright infringement intended.

The answer is 12.

2 solutions

Tran Hieu
Jan 6, 2016

Thank you! did you enjoy this puzzle?

Pi Han Goh - 5 years, 5 months ago

Not really... I was hoping that there is a website that I could go and try to solve those kind of puzzle interactively, but instead I have to use Excel...

Tran Hieu - 5 years, 5 months ago

@Ivan Koswara , any comments on this?

Pi Han Goh - 5 years, 5 months ago

@Pi Han Goh – There is unfortunately no such website that I know. I usually do my solving on MS Paint (copy the picture and paste in on MS Paint); the flood fill tool helps immensely (put a color for left and right clicks, so you can shade a cell with left click and mark a cell as empty with right click). But yes, there's still no place to solve it interactively, as far as I know.

Ivan Koswara - 5 years, 5 months ago

@Ivan Koswara – I stuck with this one. http://www.gmpuzzles.com/blog/2013/12/foxgers-den-77-cross-streams/ By stuck I found there are no solution for this. Have any of you solved that?

Tran Hieu - 5 years, 5 months ago

@Tran Hieu – You should show us your current progress.

Pi Han Goh - 5 years, 5 months ago

@Pi Han Goh – I fill the grid with black, which mean uncertain.

The red and white one are certain values for shaded/unshaded region

cell x,y means that cell at row x column y

I start from the bottom row 4422, and fill all the column which has the last info are number and I have this

After that, I link the middle part (col 6-9) to the grid above, and take into account the last 2 in col 5. Also I place the 3 in row 14 to col 12-14 (the only available rows). Then I got this:

I put the 2 in row 10, and remove the neccessary cells. Also for row 13, I deducted that the 3 could only from col 9-12 so the 1 in row 13 should be on col 1, thus col 2 row 13 should be blank. That and link the bottom left part to the grid, I have this:

For row 11, the first ? and 3 are determined. For the next "5 ?", at least 4 out of 5 cell of the "5" are also determined. With that and the last "2 2" on col 5 I have this:

Now, to link the bottom left part to the grid, in row 12, cell from col6 to col 8 need to be shaded. Then from col 8 we have last info is "1,2" so the cell 11,8 need to be white. Also in col 9 we have "1 ?" so cell 12,9 also need to be white. After that the bottom left part are disconected to the grid.

Tran Hieu - 5 years, 5 months ago

@Tran Hieu – Row 11's clue is ? 3 5 * , not ? 3 5 ? .

Ivan Koswara - 5 years, 5 months ago

@Ivan Koswara – Oh thanks a lot

Tran Hieu - 5 years, 5 months ago

Jerry Hill
Jan 17, 2016

My incorrect attempt :

I got 11 and on my second try simply added 1 to it.

column 4 = wrong.

Good try!

Pi Han Goh - 5 years, 5 months ago

Super unproductive night

Image Credit: Paw-Crafted Logic Puzzles . No copyright infringement intended.

The answer is 12.

2 solutions

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