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Sudoku - Diabolical — Solution #1

Difficulty: EXPERT Clues: 28 Hardest: BACKTRACKING 60 steps
0 / 60
NAKED SINGLE #1 R1C6 = 3 (only candidate)
NAKED SINGLE #2 R9C6 = 7 (only candidate)
NAKED SINGLE #3 R8C6 = 8 (only candidate)
NAKED SINGLE #4 R4C6 = 2 (only candidate)
NAKED SINGLE #5 R6C6 = 6 (only candidate)
HIDDEN SINGLE #6 R4C4 = 5 (only place for 5 in Row 4)
HIDDEN SINGLE #7 R6C3 = 2 (only place for 2 in Row 6)
HIDDEN SINGLE #8 R1C9 = 2 (only place for 2 in Row 1)
HIDDEN SINGLE #9 R2C2 = 2 (only place for 2 in Row 2)
HIDDEN SINGLE #10 R7C3 = 8 (only place for 8 in Row 7)
HIDDEN SINGLE #11 R9C9 = 1 (only place for 1 in Row 9)
HIDDEN SINGLE #12 R5C4 = 1 (only place for 1 in Row 5)
HIDDEN SINGLE #13 R9C1 = 5 (only place for 5 in Row 9)
HIDDEN SINGLE #14 R1C3 = 5 (only place for 5 in Row 1)
HIDDEN SINGLE #15 R8C9 = 5 (only place for 5 in Row 8)
HIDDEN SINGLE #16 R8C1 = 6 (only place for 6 in Row 8)
HIDDEN SINGLE #17 R3C2 = 6 (only place for 6 in Row 3)
HIDDEN SINGLE #18 R7C9 = 6 (only place for 6 in Row 7)
HIDDEN SINGLE #19 R6C4 = 7 (only place for 7 in Col 4)
HIDDEN SINGLE #20 R2C4 = 8 (only place for 8 in Col 4)
NAKED SINGLE #21 R2C5 = 4 (only candidate)
HIDDEN SINGLE #22 R3C3 = 4 (only place for 4 in Col 3)
HIDDEN SINGLE #23 R1C8 = 4 (only place for 4 in Row 1)
HIDDEN SINGLE #24 R6C1 = 4 (only place for 4 in Row 6)
HIDDEN SINGLE #25 R4C9 = 4 (only place for 4 in Row 4)
HIDDEN SINGLE #26 R6C7 = 1 (only place for 1 in Col 7)
LOCKED CANDIDATES POINTING #27 9 in Box 1 → Col 1; eliminate from 2 cell(s)
NAKED PAIR #28 R2C3 & R2C9 share {3,7}; eliminate from 4 cell(s)
LOCKED CANDIDATES CLAIMING #29 7 in Col 8 → Box 9; eliminate from 1 cell(s)
SIMPLE COLORING #30 Coloring (trap): 3 — cell(s) see both colors; eliminate from 1 cell(s)
LOCKED CANDIDATES POINTING #31 3 in Box 3 → Col 9; eliminate from 1 cell(s)
SIMPLE COLORING #32 Coloring (trap): 7 — cell(s) see both colors; eliminate from 2 cell(s)
XY WING #33 Pivot R5C9{7,8}, pincers R4C7 & R5C1; eliminate 3 from 2 cell(s)
NAKED SINGLE #34 R4C2 = 9 (only candidate)
HIDDEN SINGLE #35 R5C5 = 9 (only place for 9 in Row 5)
BACKTRACKING #36 Try R1C1 = 9 (trial and error)
NAKED SINGLE #37 R1C7 = 7 (only candidate)
NAKED SINGLE #38 R2C1 = 1 (only candidate)
NAKED SINGLE #39 R2C8 = 9 (only candidate)
NAKED SINGLE #40 R2C9 = 3 (only candidate)
NAKED SINGLE #41 R2C3 = 7 (only candidate)
NAKED SINGLE #42 R3C1 = 3 (only candidate)
NAKED SINGLE #43 R3C9 = 8 (only candidate)
NAKED SINGLE #44 R3C8 = 1 (only candidate)
NAKED SINGLE #45 R4C7 = 3 (only candidate)
NAKED SINGLE #46 R4C5 = 8 (only candidate)
NAKED SINGLE #47 R4C1 = 7 (only candidate)
NAKED SINGLE #48 R5C1 = 8 (only candidate)
NAKED SINGLE #49 R5C2 = 3 (only candidate)
NAKED SINGLE #50 R5C9 = 7 (only candidate)
NAKED SINGLE #51 R6C5 = 3 (only candidate)
NAKED SINGLE #52 R6C8 = 8 (only candidate)
NAKED SINGLE #53 R7C7 = 9 (only candidate)
NAKED SINGLE #54 R8C3 = 3 (only candidate)
NAKED SINGLE #55 R8C8 = 7 (only candidate)
NAKED SINGLE #56 R7C8 = 3 (only candidate)
NAKED SINGLE #57 R7C4 = 4 (only candidate)
NAKED SINGLE #58 R7C2 = 7 (only candidate)
NAKED SINGLE #59 R9C2 = 4 (only candidate)
NAKED SINGLE #60 R9C4 = 3 (only candidate)