This sudoku tutorial is really helpful. I have done numerous Sudoku puzzles most of the time during the COVID pandemic as well as reading, since it is extremely entertaining. The longest duration I have ever completed a Challenger/Hard sudoku puzzle is about 15 minutes or so, using my own techniques and stuff.
Respected Sir, I have watched many videos by other excellent teachers or experts in Sudoku. But I can tell that you are the best as you take pains to explain even if the video is long. You appear to be a borne teacher. I have benefitted immensely by your method of teaching and methods of placing small boxes and loops when you find conjugate pairs. I have few requests to make. First is that kindly do tell us in the beginning of the video your method of solving even the most difficult puzzle. What I have learnt from your Diabolical puzzle, you carry out three activities. First activity is TMB and LCR. With this you are able to get few digits by solving a cell, twins (naked pairs) and many conjugate pairs. The second activity is to see whether any row or column or block has four or lesser number of empty cells. You find out what are the numbers which can go in those empty cells. This process also helps you to get few digits by solving cells, get naked pairs and conjugate pairs. The third and last activity is to go again and carry out TMB and LCR second time by which you get few more digits solved, get few more naked pairs and conjugate pairs to help you to solve the puzzle.. This way you are able to solve the most difficult puzzle. I have few suggestions. When you are able to place a digit by solving that cell, carry out ramification i.e continue to see whether that newly placed digit helps you to get another digit in some other cell. At video time 30.06, you are able to place digit 2 in block 8 in cell Row 2 - Column 6 (R2-C6). If you had carried what effect this 2 would on the grid, you could have easily placed 2 in cell R9-C5. You need not carry out TMB & LCR again. That would have opened out many opportunities for you to solve other cells. Second suggestion is Unique Rectangles are both dangerous as they give you two or more solutions violating basic principle of Sudoku where you have to have one and only unique solution. But it also help us in removing candidates and getting digits. At video time 37.51, you found out there is three candidates 157 which can be placed in cell R2-C9. I know you are a firm believer in Thomas Snyder notation of a cell containing only two candidates. But had you atleast accept that cell has scope to have 157, you would have got a chance to have Unique Rectangle Type 1 for candidates 1,5 in four cells. That is you have 15,15, 15 and 157 in four cells of rectangle (Two 15s are in column 7 in rows 2 & 6, the third 15 is column 9 in cell R6-C9 and fourth cell of rectangle would have 157. This gives us digit 7 in cell R2-C9 by removing 15 and placing digit 7. Such methods help you to solve the puzzle in lesser time. You may consider these suggestions if you find them acceptable. Warm regards, Brig CS Vidyasagar (Retd) Secunderabad, Telangana State, India
Ohh, thank you very much. Please we would like to see you often on you tube channel. We learned a lot from your teaching how to solve Sudoku . Thanks again
It took you @18:37 to see the 7's Bottom right block... That was there the second the video started. You don't want to know what I was shouting at monitor LOL
