Monday, July 24, 2006

Sudoku Excel Helper Explained

Since I already shared my Sudoku excel helper, I might as well explain how to use it. So, let's start by solving a sudoku puzzle from here. This is rated "diabolical".

When you click on hints, this appears:

The hints sheet would show that we now know where to put the encircled 9,3,7 and 5.

After placing 9,3,7 and 5 to its location in the grid, we now have this hints below. In the first 3x3 grid, the hint showed us that the number 1 can only be placed in the last cell of the 3x3 grid. We now evaluate each 3x3 grid which gives the next four answers.

We now plot them in our puzzle.

After plotting the answers to the puzzle, we have the hints below. Evaluating the hints, vertically and horizontally, we get 3 answers.

We now plot them in the puzzle.

The hints below will lead us to five answers. Evaluating the first vertical column marked with a red rectangle, we see that 7 is an answer which eliminates 3 as an answer to that particular cell where 7 is. This gives us 3 as an answer in the 3rd cell of the first red rectagle and eliminates the other two 3's in the green 3x3 grid which results to the answer 3 on the blue rectangle. (Whew! I hope I am still understood at this point as I am getting confused myself.) Now, if we evaluate the orange rectangle, we can eliminate all the 7's in that orange rectangle. Once the 7's are eliminated, we concentrate on the pink rectangle. We get another answer, the number 7.

Plotting the five answers, we get:

The hint will now give us another answer, the number 6 and 8.

We get this:

Now the hints sheet would look like this:

Concentrate on red rectangle. We now see 5 as an answer. With this as an answer, this results to 2 more answers. See direction of the arrows. We plot the three numbers:

Hints sheet will be:

If we look at the hints above, there are no clear clues. This is the point where we realize why the puzzle is called diabolical. Confusion starts. (If you are still reading my explanations up to this point, I am deeply touched.) Now back to the puzzle, concentrate on the blue rectangle below. We'll do a trial-and-error. We know that in the two hints given by the blue box we either put 4 or 8. We assume that we put 8. Follow the green arrows. The end result are two 8's on the same horizontal 1x9 grid which contradicts to rules of Soduko.

This means that 4 is correct answer to that starting cell. So if we put 4 we now have, the puzzle is now easy to solve.

This is now the solution to the puzzle.

See also: Sudoku Trick


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