Solving Sudoku, a Japanese mind game / puzzle, has been one of my routine activities. It is a 9 x 9 matrix where some of the positions are filled. One has to fill in the remaining positions so that there are 1-9 digits in each row, coloumn and in each 9 non-overlapping matrices.
The simplicity of rules makes this puzzle attractive and complication of solving makes this addictive. The best part I feel, it does not require pre-knowledge like in the case of crosswords. There would be an uniquesolution to every game. 10 minutes of interest is guaranteed everyday. I usually fill it in the hotel during the breakfast inspite of the disappointment of the waiter, who thinks I take longer to finish. If it is unfinished, it would be finished in bus and the moment I lift my head from the paper, it would be my alighting stop.
It is being carried by most of the daily newspapers. Nowadays, as the filled positions are more, it has become too simple and can be solved without guessing at any instant of time. I think for this case a program can be written easily to solve the puzzle. But for certain puzzles, a guess was required and if the guess was wrong, there was no way to now immediately. Infact once, just when very few positions were left I realised a guess (that was made in the very beginning) was incorrect and whole puzzle has to be reworked on the line of other guess. For such cases, I feel, it would be challenging to write a program to solve it.