The New Sudoku Players' Forum

by **omg0rZ** » Tue Jan 31, 2006 3:55 pm

．５４．９７．６．
．．．４．．７．．
．．．．２．．．８
．．．３．．．９．
．１．．８．．７．
．７．．．２．．．
４．．．１９．．．
．．１．．３．．．
．９．８５．３２．

and i cant make the next step on this:

８５４１９７２６３
．６．４３８７．．
．３．．２．．．８
．４．３７１８９．
３１．．８．．７．
．７８．４２１３．
４．３．１９．．．
５．１．６３．．．
．９．８５４３２１

by **CathyW** » Tue Jan 31, 2006 4:20 pm

Would be useful to have your candidate list as well to know what you've eliminated. For the sake of argument, will assume it's as follows:

Code: Select all: {8} {5} {4} {1} {9} {7} {2} {6} {3} {129} {6} {29} {4} {3} {8} {7} {15} {59} {179} {3} {79} {56*} {2} {56*} {49} {14} {8} {26} {4} {256} {3} {7} {1} {8} {9} {256} {3} {1} {2569} {569*} {8} {56*} {456} {7} {2456} {69} {7} {8} {569} {4} {2} {1} {3} {56} {4} {28} {3} {27} {1} {9} {56} {58} {567} {5} {28} {1} {27} {6} {3} {49} {48} {479} {67} {9} {67} {8} {5} {4} {3} {2} {1}

You could use the uniqueness principle on the cells marked with *. This prinicple assumes that there is only one solution to the puzzle. Therefore r5c4 must be 9, otherwise there would be at least two solutions as r3c4, r3c6, r5c4, r5c6 could be either way round. More on this here http://forum.enjoysudoku.com/viewtopic.php?p=12309#p12309.

by **TKiel** » Tue Jan 31, 2006 4:39 pm

I solved the puzzle to the point where all solved cells were the same as listed in your grid, but without knowing what your candidate list is, as CathyW mentions, I don't know if we are looking at the same possibilities, but there should also be a naked pair in column 7 (and a hidden pair) which leads to a naked pair in row 5, which results in singles to the end.

Code: Select all: *-----------* |.54|.97|.6.| |...|4..|7..| |...|.2.|..8| |---+---+---| |...|3..|.9.| |.1.|.8.|.7.| |.7.|..2|...| |---+---+---| |4..|.19|...| |..1|..3|...| |.9.|85.|32.| *-----------* *-----------* |854|197|263| |.6.|438|7..| |.3.|.2.|..8| |---+---+---| |.4.|371|89.| |31.|.8.|.7.| |.78|.42|13.| |---+---+---| |4.3|.19|...| |5.1|.63|...| |.9.|854|321| *-----------* *-----------------------------------------------------------* | 8 5 4 | 1 9 7 | 2 6 3 | | 129 6 29 | 4 3 8 | 7 15 59 | | 179 3 79 | 56 2 56 | 49 14 8 | |-------------------+-------------------+-------------------| | 26 4 256 | 3 7 1 | 8 9 256 | | 3 1 2569 | 569 8 56 | 456 7 2456 | | 69 7 8 | 569 4 2 | 1 3 56 | |-------------------+-------------------+-------------------| | 4 28 3 | 27 1 9 | 56 58 567 | | 5 28 1 | 27 6 3 | 49 48 479 | | 67 9 67 | 8 5 4 | 3 2 1 | *-----------------------------------------------------------*

Tracy

by **Animator** » Wed Feb 01, 2006 9:50 pm

Can someone either confirm that the starting grid is correct or mention the source (and identification code) of this puzzle?

(I'm asking because the starting grid is almost symmetric... it's missing only one clue (r3c4) to be symmetric so it could be an error while copying it.)

by **tarek** » Wed Feb 01, 2006 10:15 pm

Code: Select all: . 5 4 | . 9 7 | . 6 . . . . | 4 . . | 7 . . . . . | . 2 . | . . 8 -------+-------+------ . . . | 3 . . | . 9 . . 1 . | . 8 . | . 7 . . 7 . | . . 2 | . . . -------+-------+------ 4 . . | . 1 9 | . . . . . 1 | . . 3 | . . . . 9 . | 8 5 . | 3 2 .

The puzzle is valid, non symmetrical & has only one solution. As TKiel mentioned the steps that solve the puzzle come at:

Code: Select all: *-----------------------------------------------------------------* | 8 5 4 | 1 9 7 | 2 6 3 | | 1269 26 269 | 4 3 8 | 7 15 59 | | 13679 36 3679 | 56 2 56 | 459 145 8 | |---------------------+---------------------+---------------------| | 256 4 256 | 3 7 1 | 8 9 256 | | 23569 1 23569 | 569 8 56 | 456 7 2456 | | 569 7 8 | 569 4 2 | 1 3 56 | |---------------------+---------------------+---------------------| | 4 2368 23567 | 27 1 9 | 56 58 567 | | 257 28 1 | 27 6 3 | 459 458 4579 | | 67 9 67 | 8 5 4 | 3 2 1 | *-----------------------------------------------------------------* Eliminating 5 From r3c7 (Row 2 & Box 3 Box-line interaction) Eliminating 5 From r3c8 (Row 2 & Box 3 Box-line interaction) *-----------------------------------------------------------------* | 8 5 4 | 1 9 7 | 2 6 3 | | 1269 26 269 | 4 3 8 | 7 15 59 | | 13679 36 3679 | 56 2 56 | 49 14 8 | |---------------------+---------------------+---------------------| | 256 4 256 | 3 7 1 | 8 9 256 | | 23569 1 23569 | 569 8 56 | 456 7 2456 | | 569 7 8 | 569 4 2 | 1 3 56 | |---------------------+---------------------+---------------------| | 4 2368 23567 | 27 1 9 | 56 58 567 | | 257 28 1 | 27 6 3 | 459 458 4579 | | 67 9 67 | 8 5 4 | 3 2 1 | *-----------------------------------------------------------------* Eliminating 6 From r3c1 (Row 2 & Box 1 Box-line interaction) Eliminating 6 From r3c2 (Row 2 & Box 1 Box-line interaction) Eliminating 6 From r3c3 (Row 2 & Box 1 Box-line interaction) *--------------------------------------------------------* | 8 5 4 | 1 9 7 | 2 6 3 | | 1269 26 269 | 4 3 8 | 7 15 59 | | 179 3 79 | 56 2 56 | 49 14 8 | |------------------+------------------+------------------| | 26 4 256 | 3 7 1 | 8 9 256 | | 3 1 2569 | 569 8 56 | 456 7 2456 | | 69 7 8 | 569 4 2 | 1 3 56 | |------------------+------------------+------------------| | 4 268 3 | 27 1 9 | 56 58 567 | | 5 28 1 | 27 6 3 | 49 48 479 | | 67 9 67 | 8 5 4 | 3 2 1 | *--------------------------------------------------------* Eliminating 6 From r7c2 (Row 9 & Box 7 Box-line interaction) *--------------------------------------------------------* | 8 5 4 | 1 9 7 | 2 6 3 | | 129 6 29 | 4 3 8 | 7 15 59 | | 179 3 79 | 56 2 56 | 49 14 8 | |------------------+------------------+------------------| | 26 4 256 | 3 7 1 | 8 9 256 | | 3 1 2569 | 569 8 56 | 456 7 2456 | | 69 7 8 | 569 4 2 | 1 3 56 | |------------------+------------------+------------------| | 4 28 3 | 27 1 9 | 56 58 567 | | 5 28 1 | 27 6 3 | 49 48 479 | | 67 9 67 | 8 5 4 | 3 2 1 | *--------------------------------------------------------* r5c7 Must only have 56 as valid Candidates (49 is a Naked Double in Column 7)

Tarek

The New Sudoku Players' Forum

help please

help please