This PROVEN Strategy Can Solve Hard Sudoku 

Get the rest of this puzzle pack👉👉www.buymeacoffee.com/timberlakeB/membership Timestamps 0:00 Intro 00:17 It’s Solving Time 00:29 Puzzle Story 02:18 BONUS Strategy 06:20 Solving The Purple Cell 08:32 Neat Naked Triple Trick 10:15 Using The Proven Strategy 12:29 Following The Snyder

At 11min your explanation waa fundamental for my solve! Thank you 😊

I did the whole thing in 24:52, with no help from anything except the "strategies demonstrated in this video' list. The purple cell in the upper corner was somewhat distracting, but basically the puzzle went very fast for 1/2 of it, but then slowed down. I had already found the triple, so it was nice that the list was in the proper order. It took me a while searching for the xy wing, but I knew it had to be there because I had every cell filled in with BVC, except a few having 3 candidates. I knew I had to get one of those knocked down to a BVC to be able to solve, and I did. I'm ready for the world championships. Lol.

Good puzzle. Doing it without notations and not memorizing all the bi-value cells, I had to "play" a bit with the combinations of 2 and 3s and their interactions with the 8s. Low and behold, I did "find" the XY Wing effect, because, no matter what the possible combinations of 2,3 and 8, and how they affected the 9s, a 9 always ended up in r2c5. Quite an enjoyable puzzle, but not so easy at the end. Oh ! I was forgetting to say I did find the 9 in the purple cell because, when I had the last three cells only to fill in column 1, I had a 12 remote pair in rows 3 and 6.

It's always great to see XY wings demonstrated, even though I often have trouble spotting them myself. At 11:01, it's also relatively easy to see that the highlighted cell can never be a 2 because that would force a 5 into both R2 C3 and R2 C8. But that logic is only easy to see because so much of the puzzle has already been solved. Noticing the XY wing would be a lot more useful in a puzzle where the technique appears earlier in the solve, and those are the ones I struggle with.

Good fun. One slightly tricky step (51 = row 5 column 1): 51, 42, 29, 36, 53, 56, 54, 44, 84, 74, 45, 65, 66, 55, 26, 68, 99, 98, 88, 89, 48, 59, 57, 81, 93, 21, 22, 91, 92, 11, 19, 47, 49, 79, 12 (XY-Wing), 27, 35, 25, 38, 28, 87, 78, 17, 18, 23, 85, 75, 82, 83, 62, 61, 32, 31, 63, 72. This one led to a fairly elegant spin-off: 004 200 000 060 030 070 005 400 806 000 000 709 040 050 080 506 000 000 708 006 500 090 080 040 000 007 300 004200000060030070005400806000000709040050080506000000708006500090080040000007300 HoDoKu rating: Hard 1084. Andrew Stuart rating: Tough Grade 112. =========== And here's a less elegant but more challenging variation: 004 020 000 060 100 070 005 030 806 000 000 709 040 000 080 506 000 000 708 040 500 090 005 040 000 060 300 004020000060100070005030806000000709040000080506000000708040500090005040000060300 HoDoKu rating: Unfair 1708. Andrew Stuart rating: Very Hard Grade 269.

Picking 5 in r1c2 leads to a repeated 5 in r1c8? That’s how I did it. Missed that xy wing.

I thought I was going to have to look up the solutions to the first four puzzles, to resolve R1C1. Fortunately not; I figured that this would be the case when I got a 19 pair in the top two corners. The puzzle was straightforward, with a Y-wing in the endgame to resolve everything. 7:10 I misread the rule. For some reason, I thought that this was puzzle 5, and we had to go back to the other four puzzles.

...par(1,8) y tercia(3,4,7) en 9a fila ent (9,2)=3; tercia(1,2,9) en 6a fila dentro del bloque 4 ent (5,3)=7 (9,3)=4 (9,1)=7 (2,2)=7 (2,1)=4 quedando la tercia (2,5,9) en el bloque 7; par(3,5) en 5a col dentro del bloque 8 ent (8,4)=1 (7,4)=7 (4,5)=7 (6,5)=4 (5,4)=8 (4,4)=9 (5,6)=2 (6,6)=5 (5,5)=1; pares (8,9) en 5a col y (1,6) en 6a col dentro del bloque 2; (2,9)=6 (2,6)=1 (3,6)=6 (8,8)=7 (5,9)=5 (5,7)=9 (6,8)=8 quedando la tercia (1,2,4) en 4a fila dentro del bloque 6; (9,8)=1 (9,9)=8 (1,1)=9; único lugar (8,9)=4 par(1,2) en 4a fila ent (4,8)=4 (1,9)=1 (4,9)=2 (7,9)=9 (4,7)=1 Situación X-Y Wing en 1er y 3er bloque: (1,2)=(5,8) (2,3)=(2,5) & (2,7)=(2,8) ent (1,7)=3 (1,8)=5 (1,2)=8 (2,3)=5 (2,7)=8 (2,5)=9 (3,5)=8 formándose el par(1,2) en 3a fila dentro del bloque 1 ent (3,8)=9 (2,8)=2 (7,8)=3 (7,5)=5 (8,5)=3 (8,7)=2 (8,3)=9 (6,3)=2 (6,1)=1 (6,2)=9 (3,1)=2 (3,2)=1 (8,2)=5 y (7,2)=2

13 minutes, now to watch the video :) 😺

This was too hard for me, because I kept coming to a dead end. I tried twice. It was still a good exercise, though.