The New Sudoku Players' Forum

[djape]

If you are interested in Samunamupure (Killer Sudoku) puzzles, visit
http://www.djape.net/killer-sudoku/ where you can find a brand new Killer Sudoku puzzle EVERY DAY!

[CathyW]

Thanks Djape - I've found them and printed them out to have a go. Managed Wednesday's and Thursday's eventually but am stuck on today's

Grid so far is:
xx4 x1x 789
987 x4x x1x
1xx 897 x4x
xx3 758 921
xxx 123 864
x1x 469 573
xxx 984 15x
xxx xx1 xxx
xx1 xx2 xx8

I've got quite a lot of pairs and triples as candidates but can't seem to move on from here. Any suggestions?

[Karyobin]

Sorry, in my considered opinion, that's horrible.

[tso]

Nothing exotic is required to solve this one. You've got to alternate bewteen eliminating candidates based on the sums, then advance the puzzle using normal Sudoku logic.

For example, starting from the position you gave, normal sudoku logic gives these candidates:

Code: Select all

{2356}   {2356}   {4}      {23}     {1}      {56}     {7}      {8}      {9}     
{9}      {8}      {7}      {23}     {4}      {56}     {236}    {1}      {256}   
{1}      {2356}   {256}    {8}      {9}      {7}      {236}    {4}      {256}   
{46}     {46}     {3}      {7}      {5}      {8}      {9}      {2}      {1}     
{57}     {579}    {59}     {1}      {2}      {3}      {8}      {6}      {4}     
{28}     {1}      {28}     {4}      {6}      {9}      {5}      {7}      {3}     
{2367}   {2367}   {26}     {9}      {8}      {4}      {1}      {5}      {267}   
{245678} {245679} {25689}  {56}     {37}     {1}      {246}    {39}     {267}   
{4567}   {45679}  {1}      {56}     {37}     {2}      {46}     {39}     {8}     

R78c9 must total 9, so the candidate 6 can be removed from both. Several naked pair exclusions and a locked candidate exclusion follow:

Code: Select all

{2356}  {2356}  {4}     {23}    {1}     {56}    {7}     {8}     {9}     
{9}     {8}     {7}     {23}    {4}     {56}    {23}    {1}     {56}   
{1}     {2356}  {256}   {8}     {9}     {7}     {23}    {4}     {56}   
{46}    {46}    {3}     {7}     {5}     {8}     {9}     {2}     {1}     
{57}    {579}   {59}    {1}     {2}     {3}     {8}     {6}     {4}     
{28}    {1}     {28}    {4}     {6}     {9}     {5}     {7}     {3}     
{2367}  {2367}  {26}    {9}     {8}     {4}     {1}     {5}     {27}   
{24578} {24579} {2589}  {56}    {37}    {1}     {46}    {39}    {27}   
{457}   {4579}  {1}     {56}    {37}    {2}     {46}    {39}    {8}   

R8c3 cannot be 2, as r7c23 cannot total 16.
R8c3 cannot be 8, as r7c23 cannot total 10.

More 'normal' sudoku logic brings you to:

Code: Select all

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

{356}   {2356}  {4}     {23}    {1}     {56}    {7}     {8}     {9}     
{9}     {8}     {7}     {23}    {4}     {56}    {23}    {1}     {56}   
{1}     {2356}  {26}    {8}     {9}     {7}     {23}    {4}     {56}   
{46}    {46}    {3}     {7}     {5}     {8}     {9}     {2}     {1}     
{57}    {579}   {59}    {1}     {2}     {3}     {8}     {6}     {4}     
{2}     {1}     {8}     {4}     {6}     {9}     {5}     {7}     {3}     
{367}   {2367}  {26}    {9}     {8}     {4}     {1}     {5}     {27}   
{8}     {24579} {59}    {56}    {37}    {1}     {46}    {39}    {27}   
{457}   {4579}  {1}     {56}    {37}    {2}     {46}    {39}    {8}     

R7c1 must be 3 and r9c1 must be 4 in order for their enclosure to add to 15. Lot's of easy singles follow:

Code: Select all

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


{5}    {23}   {4}    {23}   {1}    {6}    {7}    {8}    {9}   
{9}    {8}    {7}    {23}   {4}    {5}    {23}   {1}    {6}   
{1}    {236}  {26}   {8}    {9}    {7}    {23}   {4}    {5}   
{6}    {4}    {3}    {7}    {5}    {8}    {9}    {2}    {1}   
{7}    {59}   {59}   {1}    {2}    {3}    {8}    {6}    {4}   
{2}    {1}    {8}    {4}    {6}    {9}    {5}    {7}    {3}   
{3}    {267}  {26}   {9}    {8}    {4}    {1}    {5}    {27}   
{8}    {2579} {59}   {6}    {37}   {1}    {4}    {39}   {27}   
{4}    {79}   {1}    {5}    {37}   {2}    {6}    {39}   {8}   

R7c2 cannot be 2 or 6 because of the summation rule, so it must be 7. Only naked singles are required to finish the puzzle:

Code: Select all

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

[Karyobin]

Ah. Y'see, in my codeine-addled state I neglected to take in the word 'Killer'. Silly me.

Still say it's hard otherwise.

[CathyW]

R8c3 cannot be 8, as r7c23 cannot total 10.

Thank you Tso - this was the key thing I was missing. It all fell into place after that

[xander]

Wonderful new Sudokus at your site, djape!

Xander
http://sudokuportal.com

[Zeb]

djape, nice Samurai X

btw, save it as GIF instead of PNG and you'll save about 20KB