Crack Hard Sudoku Puzzles With the Skyscraper Pattern

Lesson #13: Here are two examples of the skyscraper pattern, one where the base is across a row, and the other when the base is down a column. I go through the logic of how this works. You can use this technique in your chest of tools to solve harder sudoku puzzles. I hope you enjoy!

[@victorpitigliano1973]

but at 3.06 if the 7 in H2 is false, the 7 in H6 might be true so the 7 in H7 isn't obligated to be true. I don't understand

[@snajper4141]

It can't be. Because in H2 and H7 the only possible digits are 2 and 7. So if one of them are 2 or 7, the other one must be oposite. That's why all other 2 and 7 in the H row can be eliminated.

[@bobadams1696]

I really appreciate the added explanation on this “next level” tool to solving puzzles. I know it may be too draw out for some, but there it maybe the only way I and others will get it.

[@LearnSomethingNewEveryDay]

Thanks Bob, I really appreciate your feedback! It also takes me longer to edit into the video all the circles and arrows, hopefully that helps illustrate what I am doing. Thanks for the comment!

[@reethujha5445]

Thanqq... Tried solving a sudoku which was looking impossible to solve, using this method...and my sudoku was solved in few seconds... It's awesome...

[@ertanyesildas]

Hello, i've listened and tried to learn this from videos, and even read on internet. But this video is finally where i understand it. Thank you 🙂

[@LearnSomethingNewEveryDay]

Thank you so much for the feedback, I really appreciate it!

[@kikilynn1167]

Thanks for the video? Do the 4 points that make up the skyscraper have to be in separate blocks for this to work?

[@SaraMHouse]

I had to do further research for this as i was also confused and most tutorials don't specify. Sudoku Guy has a good tutorial on Skyscrapers., he said the rows/columns must be in separate blocks!

[@rkhrg]

Very well explained excellent

[@chaosme1ster]

1st example: both top-7's could be true (A7 and B2), with row H having a 7 in column 6. The argument holds when reasoning from False > True > F > T, but fails in the T>F>T>F case. I.e. if A7 is False then B2 is True, but the reverse doesn't hold. Or am I missing something? The problem is that H2 and H7 don't have a strong link because of H6. EDIT: there *is* a strong link once you identify the matched 2-7 pair in H2/H7 (which eliminates all other 7's from row H). But you do that only afterwards. So yes, the skyscraper argument eventually holds, but only if you had presented it in the right order.

[@lheyrafprovincelife]

Nice content, very helpful

[@truemomo]

Great video, thank you! Just a question regarding the “roof” of the pattern. n first example, why couldn’t c7r1 & c2r2 both be sevens? They don’t share the same row? In the second one, c4r5 & c5r3 could both be threes?

[@trev2076]

I’m just learning this technique myself, but aside from the presence of linked pairs, I think it might not matter if both points of the roof are true. The skyscraper seems like it is only used as a way to eliminate candidates that can see both points of the roof. If either point is true, or if both are true, it still eliminates any candidates that see both.

[@davidgoldsmith7475]

Looking at the comments below is it therefore true that this only works if the "base" is a matching pair ?

[@jeancerrien3016]

Thank you for the nice explanation. I liked the second example better: some of the logic you applied at the end of the first could have been applied before you invoked the skyscraper.

[@beauistologio1675]

Finally got Helpful explanation

[@francoisepichot181]

Hello Thank you so much for your very clear explanations ! Where can I find all your lessons for classic sudoku please ?

[@akiladevi6225]

I learnt a new technique skyscrapers from you Mam Thanks a lot

[@danivaljean9073]

thanks! what is the app use? :)

[@mbillmiller1]

Hi. Just found your channel, your stuff is EXCELLENT! Thanks! Just starting sudoku can do easy ones - watched your episode 1-6. Is there a sequence of your videos I should watch ?

[@lechj9351]

@5:28 , after elimination two 5s in cells A1and B1,the puzzle looks still unsolvable. What is the next step, please?

[@howardtoob]

Where can I find these puzzles? I went to Hoduko and there are no puzzles?

[@dysan00]

Can you let us know which sudoku solver that is? I haven't run into any that shows you what level of puzzle it is lol

[@karrarhaider6069]

H6 seven shouldn't be eliminated too?

[@jimbobago]

Yes, it is eliminated.

[@HonteleJ]

Erm why does H7 needs to be true if H2 is false? 🧐

[@badsnipertwopointoh]

H2 being false does imply H7 is true, but only because they're matching pairs which is separate from this technique. Other 2, 7 candidates on row H should have been removed already.

[@jimbobago]

You must have one of each digit in a row so if H2 is false (in other words, it's false that the digit 7 occurs in H2) then since you must have a 7 somewhere in row H and the only other possibility of a 7 is in H7, then it must be true that the 7 is in H7.

[@kikilynn1167]

There are 2-7 pairs in H2 and H7, which means that the 2's and 7's can be eliminated from H1 and H6 before even beginning the skyscraper technique. After eliminating the 2s and 7s from H1 and H6, then the only 7's remaining are in H2 and H7.

[@EdLee74]

Yes her logic of row H was confusing since there were other 7 candidates but the explanation of pairs cleared it up. If they were 2-7 pairs then this technique would work and could be dangerous assumption

[@davidgoldsmith7475]

Just realised that rather than saying if H2 is false H7 is True (which only works if they are matching pairs ) if you say if H7 is true then H2 is False. Same thing but makes more sense to me. This means they do not need to be matching pairs.

[@mingchinglin8807]

There is a third scenario. The roof cells can both be true. But the rule of elimination is correct.

[@Belle-os8if]

Exactly..why can't it be B2 true and A7 true

[@lechj9351]

Wrong, it would eliminate all 7s in H row@@Belle-os8if

[@nayfen5767]

2:25 unfortunately this is wrong here. You can't start a skyscraper by stating something is true. The first assumption must be false. Same problem at 6:20