Puzzle Description:

#1: Adam Nielson (monkeyboy) on Jan 2, 2009

I couldn't figure out a way to solve this without guessing.

Ditto. Big guessing.

agree... lots and lots of guessing

I found a way to solve this one logically with a lot edge logic. Could you post where you got stuck at?

After I did part of the 11, I tried edge logic on the 4 on the bottom. I got 2 of those 4 placed, and then I tried edge logic on every other border. I got a few eliminated squares, but that was it. Every other place I tried seemed to work. I could have kept going for many moves, seeing if I would reach a point where I knew one of them was wrong, but that becomes trial and error, and not edge logic.

The next part I did was to look at row 14. R14C1 and R14C2 will be blank with edge logic. Next, if the 3 clue in row 14 is to be at columns 10 - 12, then R14C13 will be blank and R14C14 and R14C15 would be filled in. This makes row 13 invalid as R13C12 (from the 4 clue) and R13C14 (from the 2 clue) cannot be both filled in. So columns 12 - 15 on row 14 are blanks. This allows some more line solving.

I guess the next part is one step beyond edge logic, but it's not too hard to keep all in one's head. Look at R14C3. If this is filled in, then so will R13C3 and R14C4, and R12C3 will be blank. This causes R13C4, R12C1, R12C2, and R12C4 to be blank, and R13C1 and R13C2 to be filled in which makes columns 1 and 2 invalid. So R14C3 is blank. The rest solves out easily.

So, yes, a little beyond edge logic then.

Edge logic on the bottom few rows is invaluable -- but it's not only row 15's effects on row 14 I had to consider. I had to look ahead to the effects on row 13. That did it.

No guessing here...
Multiple repetitions of Edge Logic on row 15 leaves only 6 empty.
Edge Logic on row 14 twice, followed by one Edge Logic on row 13, makes Edge Logic possible on row 14 twice again.
Next, let's see if the 2 marks on row 14 are part of the '3' clue: that would mean the '2' clue is at the far right. Filling in the clues on column 14 and 15, makes column 12 invalid; so r14c12 is a blank.
Use normal logic to complete row 14 and columns 1 to 4.
Edge logic on row 1 will help make marks on column 7.
Complete with (sometimes tricky) normal logic.

Found to be logically solvable by Gator.

Needed a handful of bits of edge logic in the bottom left to get going, then it all fell together with line logic. Fun solve!

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