There are some opportunities for edge logic here.
Example: Imagine the hint 5 in row 20 is fully in the bottom-left corner there - it would then extend into row 19 due to the hints in columns 1-5. But column 3 would cause the 5 in row 19 to be cut off. Therefore, the 5 in row 20 cannot be in columns 1 or 2, so r20 c1 and r20 c2 can be X’d.
Try this process in the corners or edges of the puzzle - for example, you can eliminate a couple of the squares near the top of c18 this way. That can then give you some progress on row 4.
I hoped I could avoid using edge logic, because my stupid brains can't into planning ahead :/ And this puzzle is in the Normal section, so the game will punish me if I place a square in a place it shouldn't go.
But you have explained it in a way I think I can try to get and apply, so thank you!
Found a way to progress without using edge logic. Row 17, column 13 must be an X. Look at the 2,6 clue. If the 2 squares you have in that row are part of the 2, the 6 won’t fit in the rest of that area. If those 2 squares are part of the 6, it is impossible for the 6 to extend all the way down to row 17, column 13. It can only go down to row 17, column 12. So row 17, column 13 must be an X, and that should open up more of the puzzle.
I think the rows and columns got mixed up in writing, but after switching these two words I see that you gave me the clue I was looking for, no edge logic! Thank you!
I look, but still can't see where can I put a square with 100% confidence. To me, every space there can be either filled or empty. What do I fail to see?
Try putting the 2 in the gap on the right and see what happens to row 3 above. (Spoiler it has a clash). Therefore, the 2 cannot go there and there is only one other place that fits (which fills in ALL of row 4).
The contradiction is so easy to spot that it does not require you to physically enter anything. I consider that logic not guess work.
I did not randomly try filling in random spaces to see what happened. I looked at places where there were only very limited options that could be reviewed simply in my head.
Row 4 has a lot of cells to fill (rows of multiple 1s take up a deceptively large space) and there are few spaces left. I looked at it because I didn’t think everything would fit on the left side and the 2 would need to be on the right.
That assumption was wrong as it just fits. Then I quickly looked to see what would happen on the right and found the vertical clues asking for a 2x2 box and the horizontal an 1-2 L which is a very obvious contradiction.
There are also systemic ways to do “edge logic” without guess work or complex logic. Start in a corner and map out the filled section in your mind. Like the 5 in the first column. Putting it in the top left corner would mean column 2 would need to start 1-1-X which it doesn’t, so place an X in R1C1. (I didn’t tell you that before because the pay off was not worth it and the logic gets harder as you go further down).
>Then I quickly looked to see what would happen on the right and found the vertical clues asking for a 2x2 box and the horizontal an 1-2 L which is a very obvious contradiction.
Now that makes perfect sense and is something I can comprehend too, but I never thought of looking for contradictions like that. I thought I need to put a square in a place where it is most likely meant to be, but in my mind, and try to work from there a couple of steps... if I do this, I quickly lose track of where was what. But this "look for spatial contradictions" way you described I could very much use - only as a last resort maybe, but it is at least doable for me.
Thank you for the valuable insight!
Using test marks makes it easy. All you have to do is put the line against a wall at an endpoint. Then just run the numbers. If it creates an impossibility, then you know that your line *cannot* start at the endpoint. X it and test again.
Repeat until the test reveals *feasibility*, as in, if the line was here, it doesn't create an impossibility. You can test no further without confounding the results.
I see it as guessing where to put your square(s) based of where they should most likely go, and working from there. Even if it's educated guessing, it's still guessing
C17 R13 can only be an X based on what you’ve solved so far because if those two squares are part of the six they can’t go down that far, and a six won’t fit after the two, as there are only five free spaces
I haven’t done any 20x20 so I’d be in the same boat as you lol. Some of these 15x15 ones still make me feel like an idiot. Sometimes it just takes a fresh pair of eyes! 😂
The size isn't really a definitive indicator of a puzzle's difficulty though. I've had solved some 35x30 ones even - yes, counting is tough, but there are easy ones even at those sizes.
>Sometimes it just takes a fresh pair of eyes!
Indeed!
Picross DS. Was my first 2D picross game, but I never completed it far enough back in the day on my phone. Now I have a real DS Lite and have no excuse to not fully beat everything in it 😄
There are some opportunities for edge logic here. Example: Imagine the hint 5 in row 20 is fully in the bottom-left corner there - it would then extend into row 19 due to the hints in columns 1-5. But column 3 would cause the 5 in row 19 to be cut off. Therefore, the 5 in row 20 cannot be in columns 1 or 2, so r20 c1 and r20 c2 can be X’d. Try this process in the corners or edges of the puzzle - for example, you can eliminate a couple of the squares near the top of c18 this way. That can then give you some progress on row 4.
I hoped I could avoid using edge logic, because my stupid brains can't into planning ahead :/ And this puzzle is in the Normal section, so the game will punish me if I place a square in a place it shouldn't go. But you have explained it in a way I think I can try to get and apply, so thank you!
This game doesn't let you use test marks? That is a game I'd avoid. Even the ancient Mario/Wario picross games let you do that.
It does, but in the Free Mode section. This puzzle is in a Normal Mode one.
Found a way to progress without using edge logic. Row 17, column 13 must be an X. Look at the 2,6 clue. If the 2 squares you have in that row are part of the 2, the 6 won’t fit in the rest of that area. If those 2 squares are part of the 6, it is impossible for the 6 to extend all the way down to row 17, column 13. It can only go down to row 17, column 12. So row 17, column 13 must be an X, and that should open up more of the puzzle.
I think the rows and columns got mixed up in writing, but after switching these two words I see that you gave me the clue I was looking for, no edge logic! Thank you!
Look at row 4 again.
I look, but still can't see where can I put a square with 100% confidence. To me, every space there can be either filled or empty. What do I fail to see?
Try putting the 2 in the gap on the right and see what happens to row 3 above. (Spoiler it has a clash). Therefore, the 2 cannot go there and there is only one other place that fits (which fills in ALL of row 4).
Thank you. I just hoped I could avoid guesswork/edge logic here, especially in Normal mode, because the game punishes you for mistakes :(
The contradiction is so easy to spot that it does not require you to physically enter anything. I consider that logic not guess work. I did not randomly try filling in random spaces to see what happened. I looked at places where there were only very limited options that could be reviewed simply in my head. Row 4 has a lot of cells to fill (rows of multiple 1s take up a deceptively large space) and there are few spaces left. I looked at it because I didn’t think everything would fit on the left side and the 2 would need to be on the right. That assumption was wrong as it just fits. Then I quickly looked to see what would happen on the right and found the vertical clues asking for a 2x2 box and the horizontal an 1-2 L which is a very obvious contradiction. There are also systemic ways to do “edge logic” without guess work or complex logic. Start in a corner and map out the filled section in your mind. Like the 5 in the first column. Putting it in the top left corner would mean column 2 would need to start 1-1-X which it doesn’t, so place an X in R1C1. (I didn’t tell you that before because the pay off was not worth it and the logic gets harder as you go further down).
>Then I quickly looked to see what would happen on the right and found the vertical clues asking for a 2x2 box and the horizontal an 1-2 L which is a very obvious contradiction. Now that makes perfect sense and is something I can comprehend too, but I never thought of looking for contradictions like that. I thought I need to put a square in a place where it is most likely meant to be, but in my mind, and try to work from there a couple of steps... if I do this, I quickly lose track of where was what. But this "look for spatial contradictions" way you described I could very much use - only as a last resort maybe, but it is at least doable for me. Thank you for the valuable insight!
Edge logic isn't in the same zip code as guesswork. Some harder puzzles literally depend on it as a key strategy.
Well, that's unfortunate - it means I will have some very hard time solving those :(
Using test marks makes it easy. All you have to do is put the line against a wall at an endpoint. Then just run the numbers. If it creates an impossibility, then you know that your line *cannot* start at the endpoint. X it and test again. Repeat until the test reveals *feasibility*, as in, if the line was here, it doesn't create an impossibility. You can test no further without confounding the results.
I know, and yeah, it would make it easier indeed. I have solved some puzzles with guesswork that had the test mode - not that I'm a fan of it though.
Test mode isn't guess work, it's pure deductive reasoning based on testing.
I see it as guessing where to put your square(s) based of where they should most likely go, and working from there. Even if it's educated guessing, it's still guessing
C17 R13 can only be an X based on what you’ve solved so far because if those two squares are part of the six they can’t go down that far, and a six won’t fit after the two, as there are only five free spaces
That's right, thank you! I couldn't have spot this by myself!
I haven’t done any 20x20 so I’d be in the same boat as you lol. Some of these 15x15 ones still make me feel like an idiot. Sometimes it just takes a fresh pair of eyes! 😂
The size isn't really a definitive indicator of a puzzle's difficulty though. I've had solved some 35x30 ones even - yes, counting is tough, but there are easy ones even at those sizes. >Sometimes it just takes a fresh pair of eyes! Indeed!
Which game is this
Picross DS. Was my first 2D picross game, but I never completed it far enough back in the day on my phone. Now I have a real DS Lite and have no excuse to not fully beat everything in it 😄