This technique is similar to the Swordfish
technique, except it looks at four
rows and columns. If four rows have a candidate in up to four cells that lie on the same four columns, then the candidate can be eliminated from all other cells in the those columns.
onsider the partial Sudoku below with the candidate 5 in the following cells.
rows 1, 3, 5, and 8
, the candidate 5 exists up to four times in each row and lies in
exactly four columns
. This arrangement of cells must contain a 5 in each column of
. So, we can eliminate the candidate 5 from
all other cells in columns 1, 2, 4, and 6
Note: You can swap columns and rows when performing this technique.
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Last Updated: 10/19/2021 8:56:23 AM CST