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Solving Classic Sudoku: 'Multiple Lines'

This is just an extended version of 'Double Pairs'. Instead of two identical cells, cells belonging to two rows/columns also follows the same result.

Take a look at Puzzle No.111. Observe the '7's.


The possible cells where '7' can be placed in the 6th and 9th boxes are marked in green.


Instead of two identical pairs of cells, it can be seen that all cells belong to the 7th and 8th column. Following the same rule as the earlier one, '7' cannot be placed in any other cell of the two columns. Hence the possible cells where '7' can be placed in the 3rd box is marked in green.


Let us just place the '4' in the 1st cell to understand this concept clearly. Using the '7's, check the possible cells where '7' can be placed in the 1st and 2nd boxes.


Using the 'Double Pairs' rule, R2C9 and R3C9 are eliminated and the unique cell left in the 3rd box has to be '7'.

Other Solving Techniques

2 comments:

Anonymous said...

why did u place the 4 in the first cell?

Rohan Rao said...

The original puzzle does not have the '4'. I have assumed that '4' to be given because then the technique can be explained very neatly :-)