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Puzzle NR_072

 
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daj95376



Joined: 23 Aug 2008
Posts: 3854
PostPosted: Sun Oct 18, 2009 5:26 pm    Post subject: Puzzle NR_072 Reply with quote
Less difficult than NR_071

Code:
NR puzzles can be solved using these techniques:

Basics:  Naked/Hidden Single, Naked Pair/Triple, Locked Candidates 1/2
Basics+: Naked Quad, Hidden Pair/Triple/Quad
VH:      BUG+1, UR Type 1, X-Wing, XY-Wing
VH+:     2-String Kite, Empty Rectangle, Remote Pair, Skyscraper,
         XYZ-Wing, finned X-Wing, UR Type 2/4


Code:
 +-----------------------+
 | 6 . . | . 4 . | 7 . . |
 | . 9 . | 6 . . | 2 . 4 |
 | . . 1 | . . 7 | . . 6 |
 |-------+-------+-------|
 | . 6 . | 5 . . | . . . |
 | 4 . . | . . . | 1 . 8 |
 | . . 9 | . . 4 | . . . |
 |-------+-------+-------|
 | 9 5 . | . 2 . | 3 4 1 |
 | . . . | . . . | 9 7 . |
 | . 7 4 | . 3 . | 8 . 2 |
 +-----------------------+

Play this puzzle online at the Daily Sudoku site
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills
PostPosted: Tue Oct 20, 2009 2:37 pm    Post subject: Reply with quote
I found two different solutions for this puzzle: a one step UR implication or 5 VH type moves.

UR 68 r78c36. To prevent deadly pattern, r8c5=6 or r8c6=1.
(6)r8c5 - (6=9)r5c5 - (9=8)r3c5 - (8)r3c4 = (8)r6c4;
(1)r8c6 - (1)r4c6 = (1-7)r4c5 = (7-8)r6c5 = (8)r6c4:
Thus, both implication of the UR force r6c4=8 to complete the puzzle.

My second solution is:
Quote:
xy-wing 37-9 with vertex 37 in r6c9, pincer 39 in r1c9 and pincer 79 is a pseudocell in col5,
x-wing 8 in r27c36,
xy-wing -238 with vertex 38 in r2c3, pincer 23 in r3c1 and pincer 28 is another pseudocell in col6,
x-wing 3 in r24c36,
BUG+1 sets r1c8=3

Ted Very Happy
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