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Tough Bugger (too hard) 042618

 
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immpy



Joined: 06 May 2017
Posts: 186

PostPosted: Thu Apr 26, 2018 1:26 pm    Post subject: Tough Bugger (too hard) 042618 Reply with quote

Darn near gave up on this one, almost stumped me. Fortunately I kept wrangling and managed to solve.....hope all enjoy it.

Code:

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

Play this puzzle online at the Daily Sudoku site

cheers...immpy
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Aj Dimonios



Joined: 01 May 2017
Posts: 324
Location: Sassari Italy

PostPosted: Thu Apr 26, 2018 10:50 pm    Post subject: Reply with quote

Hi everyone


Code:

+-----------------+----------------+-----------------+
| 16    3     9   | 146  268  5    | 7   1248   124  |
| 2     14568 148 | 3    7    168  | 9   1458   145  |
| 15    1458  7   | 149  289  189  | 23  123458 6    |
+-----------------+----------------+-----------------+
| 8     46    34  | 69   1    7    | 5   2346   2349 |
| 167   1467  2   | 5    3    69   | 8   146    149  |
| 1369  169   5   | 8    4    2    | 36  136    7    |
+-----------------+----------------+-----------------+
| 4     2589  38  | 679  5689 3689 | 1   23567  235  |
| 1359  1259  13  | 1679 569  4    | 236 23567  8    |
| 1357  1578  6   | 2    58   138  | 4   9      35   |
+-----------------+----------------+-----------------+

Play this puzzle online at the Daily Sudoku site

Solution in one step

6R2C2=>contradiction (R5C1=)=>-6R2C2=>solution.

Classic solution in two steps

Empty rectangle of 6 in box 5 with 6 of line 2 (AIC=> 6R2C2=6R2C6-6R5C5=6R4C4-6R4C2)=>-6R4C2

Code:

+-----------+------------+-------------+
| 16  3   9 | 14  26  5  | 7  8    24  |
| 2   68  4 | 3   7   68 | 9  15   15  |
| 15  158 7 | 14  29  89 | 23 234  6   |
+-----------+------------+-------------+
| 8   4   3 | 69  1   7  | 5  26   29  |
| 167 167 2 | 5   3   69 | 8  146  149 |
| 9   16  5 | 8   4   2  | 36 136  7   |
+-----------+------------+-------------+
| 4   29  8 | 679 569 3  | 1  2567 25  |
| 3   29  1 | 679 569 4  | 26 2567 8   |
| 57  57  6 | 2   8   1  | 4  9    3   |
+-----------+------------+-------------+

Play this puzzle online at the Daily Sudoku site

[6R2C2-6R2C6=6R5C6-(6=9)R4C4 and 6R2C2-6R56C2=6R5C1-(6=9)R5C6]=>contradiction (two 9 in box 5)=>-6R2C2=>Stte.

Ciao a Tutti Paolo
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immpy



Joined: 06 May 2017
Posts: 186

PostPosted: Wed May 02, 2018 4:47 am    Post subject: Reply with quote

From the first grid I played a Sashimi X-Wing (1) c34 r28 finr1c4 finr3c4=>r2c6<>1. Followed this with a Turbot Fish (6) r2c26 r4c4,r5c6. Thus, r4c2<>6. That resulted in the second grid, where I used a 2-String Kite (6) r1c1, r5c6 (connected in b2 @r1c5, r2c6). Hence, r5c1<>6. stte

cheers, immp
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Clement



Joined: 24 Apr 2006
Posts: 929
Location: Dar es Salaam Tanzania

PostPosted: Thu May 03, 2018 6:30 pm    Post subject: Tough Bugger (too hard) 042618 Reply with quote

Two Alternating Inference Chains
Code:

+-------------------------+--------------------------+-------------------------+
| a16       3         9   |b146       b268      5    | 7       1248       124  |
| 2        g14568    h48-1| 3          7       c168  | 9       1458       145  |
| 15       g1458      7   | 149        289      189  | 23      123458     6    |
+-------------------------+--------------------------+-------------------------+
| 8        f46        34  | e69        1        7    | 5       2346       2349 |
| 167       1467      2   | 5          3       d69   | 8       146        149  |
| 1369      169       5   | 8          4        2    | 36      136        7    |
+-------------------------+--------------------------+-------------------------+
| 4         2589      38  | 679        5689     3689 | 1       23567      235  |
| 1359      1259      13  | 1679       569      4    | 236     23567      8    |
| 1357      1578      6   | 2          58       138  | 4       9          35   |
+-------------------------+--------------------------+-------------------------+

(1): (1=6)r1c1 - r1c45 = r2c6 - r5c6 = r4c4 - (6=4)r4c2 - r23c2 = (4)r2c3 => - 1r2c3 followed by
Code:

+---------------------+---------------------+----------------------+
|e16       3        9 |f14      a26      5  | 7      8        g4-2 |
| 2        68       4 | 3        7      b68 | 9      15        15  |
| 15       158      7 | 14       29      89 | 23     234       6   |
+---------------------+---------------------+----------------------+
| 8        46       3 | 69       1       7  | 5      246       249 |
|d167      1467     2 | 5        3      c69 | 8      146       149 |
| 9        16       5 | 8        4       2  | 36     136       7   |
+---------------------+---------------------+----------------------+
| 4       29        8 | 679      569     3  | 1      2567      25  |
| 3       29        1 | 679      569     4  | 26     2567      8   |
| 57      57        6 | 2        8       1  | 4      9         3   |
+---------------------+---------------------+----------------------+

(2): (2=6)r1c5 - r2c6 = r5c6 - r5c1 = (6-1)r1c1 = (1-4)r1c4 = (4)r1c9 => - 2r1c9; stte
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