The New Sudoku Players' Forum

[Sandy Kimble]

I smugly thought I was really good at these, but am stumped with today's hard puzzle in the Washington Post. Can anyone suggest anything?

So far I have:

xxx|x9x|72x|
x42|371|xx9|
xxx|xx5|xxx|

831|9xx|2xx|
459|xxx|x1x|
267|1x8|x94|

xxx|7xx|1x2|
1xx|x62|x3x|
x24|x1x|xxx|

I checked the answers and these are correct, but I can't find another move.

[simes]

There's a hidden pair 7 and 9 in row 3. After that you can place a 1 in r3c9.

Simon

[masb]

There's a 7 and 9 in row 3. After that you can place a 1 in r3c9.

Simon

That is true but probably not the only next step. My solver program, Numbler (see http://www.axcis.com.au/numbler) comes up with:

Code: Select all

Box Row @ 3> r3c4x4 r3c5x4
Box Column @ 5> r7c5x5
Row Box @ 2> r1c9x8 r3c7x8 r3c8x8 r3c9x8
Quad Box r1c2=1 r3c1x3 r3c1x6 r3c2x8
Single Row r3c9=1
Box Column @ 1> r7c3x8 r8c3=5

After that it is just singles. The first step is box 3 only having 4s on row 3 so that 4 can be eliminated from r3c4 and r3c5. The next step is similar on box 5. The "x" means remove a pencil candidate and "=" means set a cell to that value. The reference cells or boxes are given between "@" and ">".