Sudoku

Rules

Fill in the blank squares in such a way that each of three expressions:

 		you, me, see

appears exactly once in each row or column. The grid already contains givens, which may not be changed.

There is only one way to solve this puzzle within these rules. Guessing is beside the point.

Methods

Elimination on Emptiness

Find a blank for which only one possible expression remains.

For example look at B2, a blank. Can B2 be me? No, because me already exists in Column B. Can B2 be you? No, because Row 2 already contains you. So with me and you eliminated, B2 must be see.

Elimination on Existence

Conversely, look for the only blank that can hold a given expression.

We know somewhere on Row 1, there must be a you. Since B1 is me, you must be either A1 or C1. But look, C1 can’t be you because you already exist in C2 (remember the rules, you can’t exist twice in the same array). So that leaves A1, which must be you.

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Copyright © 2007 by Mary Ann Schaefer
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