February 15, 2007

The Ultimate Guide to Sudoku

Yesterday was an amazing sudoku day. I spent a lot of time on www.websudoku.com, and I came up with amazing results (well atleast by my standards). I completed the easy level with a best timing of 4 minutes 11 seconds. But the best part was that I managed to complete one of the games at the "Evil" level. It took me almost 45 minutes to complete it, but it was a satisfying victory none the less.

I would like to clarify here that though you would have heard that people complete the puzzle in like a minute flat, but let me tell you, anybody who completes it in less than four minutes is a bloody freak. So 4:11 is the best non-freak timing that you can get.

Anyways, sudoku has taken over the world, probably like the craze of the rubik's cube, which hit the world when my dad was about my age. Here is what Google Trend shows us about sudoku and the rubik's cube. (link)

Solving a sudoku puzzle takes no more maths than eating an ice cream. If this is your first time, the here is a list of the strategies you could try using.

1. The first step is to look at each digit and try to complete it across the board.

2. Now after you've filled up all the places you could, you try to fill out all the numbers in each of the nine boxes.

3. After you can go no further, complete all numbers in each row and column (each has 9 digits).

4. In both of the above steps, if there are two digits left, it's not much of a problem. But if say there are 3 or 4 or even 5 digits left. The easiest way to go about it is to find out the remaining numbers, eg. 1,3,5,6. Now look at each empty slot and if you can find three of the four numbers in that row or column, then you know what number to put there.

5. After you've hit a dead end with all of the above, try each slot and see what all numbers can fit into each slot. Many times, you would find that even though a number can be placed in a lot of slots in a group, in one particular slot only one number can be placed eg. in the right top corner only number 3 can be placed.

6. If you've exhausted all possible alternatives, this is the last way to deal with it (atleast as far as I know), if you find a number can be placed in two places in a box, substitute the number in one of the places and try to find out what other numbers can thus be solved. But one thing you need to remember is that even if all the numbers fit correctly, you have not found the correct solution, you can be sure only if you find something wrong. Then you replace the first number you have substituted with the second number, which would definitely be correct now.
That is all I think. Now just start up, and if you manage to better my score, let me know. Happy sudokuing :)