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Ajò Dimonios

Joined: 01 May 2017
Posts: 339
Location: Sassari Italy

Posted: Tue Jun 06, 2017 3:22 pm Post subject: very difficult

Hi everyone

Code:

+-------------------+--------------------+---------------------+
| 12345 234568 2358 | 1459 1359 1345 | 2459 7 245 |
| 1245 245 25 | 1459 6 7 | 8 3 245 |
| 3457 345 9 | 2 8 345 | 1 45 6 |
+-------------------+--------------------+---------------------+
| 257 1 2578 | 45678 25 24568 | 3 4568 9 |
| 9 2358 2358 | 14568 1235 1234568 | 456 14568 7 |
| 6 358 4 | 15789 1359 1358 | 5 2 158 |
+-------------------+--------------------+---------------------+
| 8 235 1 | 56 4 9 | 7 56 235 |
| 245 9 6 | 3 7 1258 | 245 1458 12458 |
| 2345 7 235 | 1568 125 12568 | 24569 145689 123458 |
+-------------------+--------------------+---------------------+

Play this puzzle online at the Daily Sudoku site

Code:

+-------------+--------------------+---------------+
| 235 6 8 | 145 135 1345 | 9 7 245 |
| 1 45 25 | 9 6 7 | 8 3 245 |
| 7 345 9 | 2 8 345 | 1 45 6 |
+-------------+--------------------+---------------+
| 25 1 7 | 468 25 468 | 3 468 9 |
| 9 358 235 | 14568 1235 1234568 | 46 1468 7 |
| 6 38 4 | 7 9 138 | 5 2 18 |
+-------------+--------------------+---------------+
| 8 2 1 | 56 4 9 | 7 56 3 |
| 45 9 6 | 3 7 1258 | 24 1458 1458 |
| 345 7 35 | 1568 125 12568 | 246 9 1458 |
+-------------+--------------------+---------------+

Play this puzzle online at the Daily Sudoku site
After basics

Saluti a tutti
Paolo

JC Van Hay

Joined: 13 Jun 2010
Posts: 494
Location: Charleroi, Belgium

Posted: Wed Jun 07, 2017 9:36 am Post subject:

After basics, from the 2 solutions of the 3s : 3r6c6 -> 0 solution; r6c2=3 and basics to the end of a 1 unique solution.

For example :

11 singles
Pointing{2B3} -> -{2r789c9}; 2 singles

Code:

+----------------------+------------------------+-------------------+
| 234(5) 6 8 | 14(5) 13(5) 134(5) | 9 7 245 |
| 1 45 25 | 9 6 7 | 8 3 245 |
| 7 345 9 | 2 8 34(5) | 1 4(5) 6 |
+----------------------+------------------------+-------------------+
| (25) 1 7 | 4568 25 24568 | 3 468 9 |
| 9 358 5-3(2) | 14568 1235 1234568 | 46 468(1) 7 |
| 6 8(3) 4 | 7 9 8(13) | 5 2 8(1) |
+----------------------+------------------------+-------------------+
| 8 2 1 | 6(5) 4 9 | 7 6(5) 3 |
| 4(5) 9 6 | 3 7 28-1(5) | 24 48(15) 1458 |
| 34(5) 7 (35) | 168(5) 12(5) 1268(5) | 246 9 1458 |
+----------------------+------------------------+-------------------+

(3=5)r9c3-5r9c456=*[3r6c2=3r6c6-Kite(1r6c6=1r6c9-1r5c8=1r8c8)-5r8c8=#ER(5r3c8=#5r7c8-5r7c4=*5r8c6)-5r3c6=5r1c456-5r1c1=#Wing[2r5c3=(2-5)r4c1=#5r89c1-(5=3)r9c3]]
||
V
[1r6c6==1r8c8]-1r8c6 and [3r9c3==3r6c2==2r5c3]-3r5c3; 15 singles
Skyscraper{8C48} -> -{8r8c6, 8r9c9}; singles to the end.

That solution can be simplified as, for example :

11 singles
Pointing{2B3} -> -{2r789c9}; 2 singles

Code:

+----------------+----------------------+--------------------+
| 2345 6 8 | 145 135 1345 | 9 7 245 |
| 1 45 25 | 9 6 7 | 8 3 245 |
| 7 345 9 | 2 8 345 | 1 45 6 |
+----------------+----------------------+--------------------+
| 25 1 7 | 4568 25 24568 | 3 46(8) 9 |
| 9 358 235 | 14568 1235 1234568 | 46 46(18) 7 |
| 6 38 4 | 7 9 138 | 5 2 (18) |
+----------------+----------------------+--------------------+
| 8 2 1 | 56 4 9 | 7 56 3 |
| 45 9 6 | 3 7 1258 | 24 -45(18) 1458 |
| 345 7 35 | 1568 125 12568 | 246 9 1458 |
+----------------+----------------------+--------------------+

M-Ring{(18)r6c9, (18)C8} -> -{(45)r8c8

Code:

+----------------------+----------------------+-----------------+
| 345(2) 6 8 | 145 135 1345 | 9 7 245 |
| 1 4(5) -5(2) | 9 6 7 | 8 3 245 |
| 7 34(5) 9 | 2 8 345 | 1 45 6 |
+----------------------+----------------------+-----------------+
| (25) 1 7 | 4568 25 24568 | 3 468 9 |
| 9 38(5) 235 | 14568 1235 1234568 | 46 1468 7 |
| 6 38 4 | 7 9 138 | 5 2 18 |
+----------------------+----------------------+-----------------+
| 8 2 1 | 56 4 9 | 7 56 3 |
| 45 9 6 | 3 7 1258 | 24 18 1458 |
| 345 7 35 | 1568 125 12568 | 246 9 1458 |
+----------------------+----------------------+-----------------+

S-Wing{(25)r4c1, 2B1, 5C5} -> -{5r2c3}; 4 singles

Code:

+-----------------+-------------------+-------------------+
| 34-5 6 8 | 145 13 1345 | 9 7 2 |
| 1 4(5) 2 | 9 6 7 | 8 3 4(5) |
| 7 34(5) 9 | 2 8 34(5) | 1 4(5) 6 |
+-----------------+-------------------+-------------------+
| 2 1 7 | 468 5 468 | 3 468 9 |
| 9 358 35 | 1468 123 123468 | 46 1468 7 |
| 6 38 4 | 7 9 138 | 5 2 18 |
+-----------------+-------------------+-------------------+
| 8 2 1 | 56 4 9 | 7 56 3 |
| 4(5) 9 6 | 3 7 128(5) | 24 18 148(5) |
| 345 7 35 | 1568 12 12568 | 246 9 1458 |
+-----------------+-------------------+-------------------+

Swordfish{5R238} -> Pointing{5B1} -> -{5r3c2}; 11 singles

Code:

+-----------+------------------+------------------+
| 3 6 8 | 45 1 45 | 9 7 2 |
| 1 45 2 | 9 6 7 | 8 3 45 |
| 7 45 9 | 2 8 3 | 1 45 6 |
+-----------+------------------+------------------+
| 2 1 7 | 46(8) 5 46-8 | 3 46(8) 9 |
| 9 8 5 | 46(1) 3 2 | 46 46(1) 7 |
| 6 3 4 | 7 9 18 | 5 2 18 |
+-----------+------------------+------------------+
| 8 2 1 | 56 4 9 | 7 56 3 |
| 45 9 6 | 3 7 5-18 | 2 (18) 1458 |
| 45 7 3 | -56(18) 2 1568 | 46 9 45-18 |
+-----------+------------------+------------------+

Skyscrapers Loop{(18)C48} -> -{8r4c6, (56)r9c4, (18)r8c6.r9c9}; stte

Ajò Dimonios

Joined: 01 May 2017
Posts: 339
Location: Sassari Italy

Posted: Wed Jun 07, 2017 10:15 am Post subject:

1 fin x-wing –1 R9C9.
3 x- wing (line 3 and line 5)-3 R1C6,-3 R5C2,-3 R5C6.
If 2 is true in R1C1=> contradiction, in column 3 there are two 5 sure then 2 is false and can be eliminated.

Code:

+------------+----------------+---------------+
| 35 6 8 | 145 13 145 | 9 7 2 |
| 1 45 2 | 9 6 7 | 8 3 45 |
| 7 345 9 | 2 8 35 | 1 45 6 |
+------------+----------------+---------------+
| 2 1 7 | 468 5 468 | 3 468 9 |
| 9 58 35 | 1468 123 12468 | 46 1468 7 |
| 6 38 4 | 7 9 138 | 5 2 18 |
+------------+----------------+---------------+
| 8 2 1 | 56 4 9 | 7 56 3 |
| 45 9 6 | 3 7 258 | 24 1458 1458 |
| 345 7 35 | 1568 12 12568 | 246 9 458 |
+------------+----------------+---------------+

Play this puzzle online at the Daily Sudoku site

If 6 is true in R5C4=>contradiction, in line 7 there are two 5 sure then 6 is false and can be eliminated.
If 4 is true in R8C8=> contradiction, R6C9 is empty then 4 is false and can be eliminated.
If 5 is true in R8C8=>contradiction, R6C9 is empty then 5 is false and can be eliminated.
If 5 is true in R9C3=> contradiction, in line 6 there are two 6 sure then 5 is false and can be eliminated.

Code:

+---------+-------------+-------------+
| 3 6 8 | 45 1 45 | 9 7 2 |
| 1 45 2 | 9 6 7 | 8 3 45 |
| 7 45 9 | 2 8 3 | 1 45 6 |
+---------+-------------+-------------+
| 2 1 7 | 468 5 468 | 3 468 9 |
| 9 8 5 | 14 3 2 | 46 146 7 |
| 6 3 4 | 7 9 18 | 5 2 18 |
+---------+-------------+-------------+
| 8 2 1 | 56 4 9 | 7 56 3 |
| 45 9 6 | 3 7 58 | 2 18 1458 |
| 45 7 3 | 1568 2 1568 | 46 9 458 |
+---------+-------------+-------------+

Play this puzzle online at the Daily Sudoku site

If 5 is true in R9C9=>contradiction, R8C6 is empty then 5 is false and can be eliminated.
If 8 is true in R9C9=> contradiction, in line 6 there are two 1 sure then 8 is false and can be eliminated.

Solution=>stte.

Ajò Dimonios

Joined: 01 May 2017
Posts: 339
Location: Sassari Italy

Posted: Wed Jun 07, 2017 1:47 pm Post subject:

Hi everyone

The same solution with AIC, discontinuous nice loop and x-color
1 fin x-wing –1 R9C9.
3 x- wing (line 3 and line 5)-3 R1C6,-3 R5C2,-3 R5C6.
AIC (2)R2C3=(2-3)R5C3=(3)R9C3-(3)R9C1=(3)R1C1=>-2 R1C1.

Code:

Play this puzzle online at the Daily Sudoku site
Discontinuous nice loop (6)R5C4-(6)R5C7=(6)R9C7-(6)R9C46=(6)R7C4-(6)R5C4=>-6 R5C4.
Discontinuous nice loop (4-1)R8C8=(1)R5C8-(1=8)R6C9-(8)R89C9=(8)R8C8-(4)R8C8=>-4 R8C8.
Discontinuous nice loop (5-1)R8C8=(1)R5C8-(1=8)R6C9-(8)R89C9=(8)R8C8-(4)R8C8=>-5 R8C8.
x-color (5) R5C2(green), R5C3(yellow), R1C1(green),R3C6(green),R2C9(green),R7C8(green) and R9C4(green)=> -5R9C3 “see” R5C3(yellow) and R9C4(green).

Code:

Play this puzzle online at the Daily Sudoku site
x-color ( 8 ) R4C8(yellow), R6C9(green), R6C6(yellow) and R9C4(yellow), => -8R9C9 “see” R6C9(green) and R9C4(yellow).
Solution=>stte.

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