How To Solve Hard Sudoku Puzzle Using Sue De Coq - SHC 173 

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Thanks for solving my puzzle and for giving me the opportunity to make the June smarty party pack!

Wow ! This one was beyond me. Great demo.

After a long day out in the smoke & humidity, it was a pleasant surprise to find a new ??? waiting. I didn't have much in the way of problems with this one (rated unfair vs extreme). I'll watch the video tomorrow when there's no distractions.

5:32 Basically what you are looking at is: 8@VII4 => 8@I3, 9@VII4 => 9@I3, therefore I3 can only be an 8 or a 9. This is one of those things that would take me ages to spot with the toolset that I use.

Feeling so satisfied after doing it on my own . Actually ,when i was unable to proceed further after filling the pencil marks and just finding x wing on 1' s , i then thought of watching ur video , as soon as i heard u talking abt the technique SDC, I stopped watching urs and clicked on sudoku swami's tutorial related to Sue de Coq. And then i tried on my own .If i remember correctly , i applied SDC in three boxes 7, 9 and 5. Then i guess i found 79 pair in col 5 Wow! Great puzzle. Now let me watch ur video.

6:30 don’t need SDC here. You know that the only place for the 89 from row 8 column 1 within box 1 is in row 1 column 3 so you can use this knowledge to remove 67 from row 1 column 3. Not sure what that method is called but much easier than SDC. However this is a good way to illustrate SDC though!

Wow, I managed to crack that using the 89. I've got to say I have learned quite a lot from you with these series of puzzles, even though I don't always comment.

I'm trying it before watching the video. I hope I detect the logic, even though I don't remember the Sue De Coq pattern. Okay, it's done. I began by filling in the six-digit rows and columns. I got 789 triples in the rows. (I knew I was supposed to do something with them, but couldn't figure out what. An 89 cell in block 2 later on didn't help.) Then I went to cornermarking. I got an immediate X-wing in 1s that clipped a few. In 5s, an empty rectangle clipped a couple 5s. 7s gave me a finned swordfish that clipped a digit. (The 789 triples formed two of the rows.) My first digit was a naked 6 in block 5, thanks to the empty rectangle, and then a 5 in block 4. A 237 XYZ-Wing (Is that what it's called?) clipped a 2 in block 6. Stuck as I was, I continued to fill out the grid. I finally bifurcated on a 18 in R7C6. 1 led quickly to a collision, and I placed 8. That finally cracked the puzzle. 0:20 Yes, I did place the 1 very early, long before the 6. I just didn't notice the blue 1 when I was backtracking to tell my story. I think that the 1, 6, and 5 were the only digits I placed before bifurcating. 2:10 I didn't see the 56 pair. It was later. The empty rectangle left a pointing pair in 5s that removed the 5 from R4C5, leaving the naked 6. Then I placed the 5 in R4C2. 2:40 The finned swordfish in 7s is visible in the grid. I don't know how useful it was. 3:00 Ah, the advantage of a clutterless grid. I never saw the skyscraper. However, 5 in row 7 was limited to columns 1 and 9. Consequently, the empty rectangle did the same thing. Since I hadn't spotted the 56 pair, the result was a pointing pair that removed the 5 from R4C5. 4:20 Yes, my second and third digits. 5:50 A jumble of cells plus a 36 pair. I couldn't do anything with the latter, though. 10:00 I spent a little time studying my grid, having paused the video. Originally, I thought of using letters (H and I) for 8 and 9. I might have hit upon the logic if not the name. Defining H to be the digit in R8C1 (89) and I to be the other of 8 and 9, that would lead to a 367I quad in block 1, placing H in R1C3. With 7 and I restricted in that block to column 1, I could remove 7, 8, and 9 from the rest of column 1. Thanks for the video.

By mistakenly l missed 3 in r3c7(389 to 89) and l got 1s X wing and 5s Skyscraper puzzle get solved., notable to find SDC, then I watched vedio l saw SDC and my mistake. Once l saw answer l dropped. In comment solving with 89 also is good way. My solve this when l missed the 3, I started from there. If 3 is there or not r2c5 is 7. Puzzle solved. Any way lesson for me to find Quinn's SDC, It will help in future. Thanks.