The New Sudoku Players' Forum

[lthjason123]

Here are two sudoku puzzles.

1.
x83 1xx 95x
x9x xxx 26x
5xx 94x xxx

97x xxx xxx
xx8 273 x9x
3xx xxx x78

xxx 681 xx9
146 xxx xxx
839 xx4 61x

2.
1x2 54x x9x
6x9 21x 5xx
xx4 8x9 x12

xx8 xxx 3xx
xx7 xxx 1xx
xx5 xxx 9xx

4x6 3x8 251
xx3 x21 4x9
xx1 x54 x37

Please help me to solve these puzzles.

[Shazbot]

Puzzle 1:

Code: Select all

 *-----------------------------------------------------------------------*
 | 2467    8       3     | 1       26      267   | 9       5       47    |
 | 47      9       147   | 3578    35      578   | 2       6       1347  |
 | 5       126     127   | 9       4       2678  | 1378    38      137   |
 |-----------------------+-----------------------+-----------------------|
 | 9       7       1245  | 458     156     568   | 1345    234     123456|
 | 46      156     8     | 2       7       3     | 145     9       1456  |
 | 3       1256    1245  | 45      1569    569   | 145     7       8     |
 |-----------------------+-----------------------+-----------------------|
 | 27      25      257   | 6       8       1     | 3457    234     9     |
 | 1       4       6     | 357     2359    2579  | 3578    238     2357  |
 | 8       3       9     | 57      25      4     | 6       1       257   |
 *-----------------------------------------------------------------------*


Naked triple in row 7, followed by naked pair in box 9
Naked quads in column 7 (or you could look for a hidden pair in column 7 instead)
Then look for locked candidates (1s and 4s in box 3, 5s in box 9)
You should now be able to start placing numbers

Puzzle 2:

Code: Select all

 *--------------------------------------------------------------------*
 | 1      378    2      | 5      4      367    | 678    9      368    |
 | 6      378    9      | 2      1      37     | 5      478    348    |
 | 357    357    4      | 8      367    9      | 67     1      2      |
 |----------------------+----------------------+----------------------|
 | 29     12469  8      | 14679  679    2567   | 3      2467   456    |
 | 239    23469  7      | 469    3689   2356   | 1      2468   4568   |
 | 23     12346  5      | 1467   3678   2367   | 9      24678  468    |
 |----------------------+----------------------+----------------------|
 | 4      79     6      | 3      79     8      | 2      5      1      |
 | 578    578    3      | 67     2      1      | 4      68     9      |
 | 289    289    1      | 69     5      4      | 68     3      7      |
 *--------------------------------------------------------------------*


There's a naked triple in column 1. Once you have that (eliminate from column 1 and box 4) everything just falls into place.

[lthjason123]

I am so sorry that I cannot understand what you said about naked quads.
Can you explain more detailedly?

[Crazy Girl]

Shazbot wrote: a NAKED pair is where two cells in the same row/column/box contain ONLY the same two candidates. These candidates may occur in OTHER cells in that group, but are the ONLY ones in those two cells. They may be removed from the other cells.

Example: 1 25 236 | 367 254 568 | 9 467 25
2 and 5 are the naked pair, and those numbers can be removed from all other cells (leaving a "naked single", 4, in column 5)

a HIDDEN pair is where two numbers can ONLY be placed in the same two cells in a row/column/box. There may be other candidates in those two cells, but those are the only places for those two numbers to go. The other candidates in those cells can be removed.

Example: 2347 4589 348 | 1 349 3459 | 48 2478 6
2 and 7 are a hidden pair, only able to be placed in the same two cells. All other candidates from those cells can be removed.

a NAKED Quad is where four cells in some row/column/box contain ONLY four candidates, each cell does not have to contain all four candidates. These candidates may occur in OTHER cells in that row/column/box, but are the ONLY ones in those four cells. So they may be removed from the other cells.

Column 7 reads: 9 2 1378 1345 145 145 34 3578.
Now you have 4 numbers that only appear in 4 cells.

Note Column 7 Row 8 is {3, 4} as you can remove the Naked triple in Box 7 column 7 from the rest of Row 7 as these three numbers must appear only in Box7column 7.

If you need to get more information on the terms used in this forum check out:
Angusj
or
Simes Clara

[Shazbot]

a NAKED Quad is where four cells in some row/column/box contain ONLY four candidates, each cell does not have to contain all four candidates. These candidates may occur in OTHER cells in that row/column/box, but are the ONLY ones in those four cells. So they may be removed from the other cells.

Column 7 reads: 9 2 1378 1345 145 145 34 3578.
Now you have 4 numbers that only appear in 4 cells.

almost, but not quite.

If the four numbers ONLY appear in the same 4 cells, then it may be a HIDDEN quad (and those cells can contain other numbers). A NAKED quad has some combination of the same 4 numbers in the same 4 cells, with NO OTHER numbers in those cells, but those 4 numbers may also be in other cells in that group. That's why it's useful - you can remove those numbers from the remaining cells.

You got the first definition correct, but not the second - "now you have 4 numbers that only appear in 4 cells". Some of those numbers appear in other cells as well (but won't after you eliminate them as a result of this find).

Before you've done the elimination, you'll have (this will read top to bottom in the puzzle, not left to right):
9 2 1378 1345 145 145 34 578 6
(you've removed the 5 and 7 from r7c7 with the naked triple in row 7, and then removed the 3 from r8c7 with the naked pair that results)

Now, the 1345 145 145 34 are the 4 cells containing some combination of the same 4 numbers with no other numbers. So 1345 can be removed from all other cells in that column, and you're left with
9 2 78 1345 145 145 34 78 6

These are much harder to spot than naked pairs and triples, so you may have had better luck spotting the HIDDEN PAIR in that column instead - after the eliminations on r7c7 and r8c7, there are only two cells that contain candidates 7 and 8, and they're the same two cells. So 7 MUST go in one of them, and 8 MUST go in the other. That's a hidden pair, and other candidates in those two cells can be removed.

Crazy Girl gave you links to a couple of sites that explain these - I very highly recommend visiting, printing, bookmarking them. They have excellent walk-throughs and examples.

[Guest]

Code: Select all

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



[Guest]

Code: Select all

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



[Cec]

"...a NAKED Quad is where four cells in some row/column/box contain ONLY four candidates, each cell does not have to contain all four candidates..."

"..If the four numbers ONLY appear in the same 4 cells, then it may be a HIDDEN quad (and those cells can contain other numbers). A NAKED quad has some combination of the same 4 numbers in the same 4 cells..."

The above parts of this interesting thread got me pondering as to the preferred wording to explain"quads" (includes "triples" also).

I tend to favour "Crazy Girl's" above wording which more closely follows the angusj explanation requiring a prescribed number of candidates, in this case four cells for a quad (or a combination of these numbers) to appear in a prescribed number of cells in a group - in this case four cells. This seems better than saying the four numbers must appear in the "same 4 cells". I know what you are meaning but no four cells are the same.

As another fellow Aussie, have you started watching cricket again?.

Cheers Cec

[Shazbot]

Hey Cec,

working 3 days a week, with a 4YO in kindy 3 days, plus my out-of-work-computer-addiction, I'm usually too exhausted to watch much of anything (except Finding Nemo, which we see up to 4 times a day....well, sometimes it seems that way)! I USED to enjoy watching cricket - Warnie turned me off it a bit - maybe I'll catch up a little with the one-dayers through Summer.

[Cec]

I USED to enjoy watching cricket ..."

So did I until Peiderson and Flintoff went on the warpath. My question on cricket was a bit subtle as to whether the current "West Indies" series had rekindled your interest if it had also taken a hammering like mine. Can't wait for the re-match against the mighty 'Poms' on our own territory.

Cec

[Crazy Girl]

I USED to enjoy watching cricket ..."

So did I until Peiderson and Flintoff went on the warpath. My question on cricket was a bit subtle as to whether the current "West Indies" series had rekindled your interest if it had also taken a hammering like mine. Can't wait for the re-match against the mighty 'Poms' on our own territory.

Cec

If you are going to name two great sportsman in British Cricket at the moment, please spell their names correctly (Kevin Pieterson and Andrew 'Freddie' Flintoff) and it has been a pleasure to watch them play some great cricket

ps the rematch should be a stonker !!!

[rubylips]

If you are going to name two great sportsman in British Cricket at the moment, please spell their names correctly (Kevin Pieterson and Andrew 'Freddie' Flintoff)

Er, make that Pietersen. Of course, it's not a name you encounter very often in England.

[QBasicMac]

(A solution)

Dear Anonymous: Your submissions of completed puzzles do not impress anyone on this forum and are not helpful in the least.

The forum regulars (to whom I don't belong) are very polite here and will fail to point that out. But I will.

To be of any help, you must show how you arrived at the solution. Anyone here can immediately solve nearly any puzzle with the assistance of software and, for easy puzzles like the one you solved, do not even require an automated scratch pad.

In other words, <yawn! zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz>

Mac

[Cec]

If you are going to name two great sportsman in British Cricket at the moment, please spell their names correctly (Kevin Pieterson and Andrew 'Freddie' Flintoff) and it has been a pleasure to watch them play some great cricket
ps the rematch should be a stonker !!!

Hi Crazy Girl,
Firstly, I must thank rubylips for showing both of us the correct way to spell Kevin Pietersen's name - correct spelling of words is not always easy such as the word "sportsmen".

For the record I have previously acknowledged in a PM that the recent "Ashes" series was the best I can remember and that the better side won. This thread may help you understand this. Out of curiosity what does "stonker" mean?

Cec

[Crazy Girl]

stonker means great