A sudoku checking program in C :)
It just started when my younger bro, Shafeeq who reads hacker news everyday, found a little interesting blog post. It was about the authors experience in applying for an internship at Google. The candidate was asked to write a program to check a completed sudoku during the telephone interview for errors, in his favorite programming language. I asked bro, “Why don’t you give it a try?!”. He’s now in 11th standard and started coding in C++ which he learns in Computer Science subject. He came up with the code in one day, and then it was my turn to do that
Here’s the way I solved the problem and it’s in pure C.
You can find the code here, in github. The input is given as a plain text file that contains 9×9 numbers separated by space. A sample input is given below:
7 2 3 8 4 6 1 5 9
6 1 5 3 9 2 4 7 8
8 4 9 7 1 5 6 3 2
3 7 8 6 5 4 9 2 1
1 9 4 2 8 7 3 6 5
2 5 6 9 3 1 8 4 7
5 6 1 4 7 9 2 8 3
4 8 7 1 2 3 5 9 6
9 3 2 5 6 8 7 1 4
And to check for errors, please call the program with the file as argument, like this -
$checksudoku <data_file>
Hope you enjoyed it, Please go through the code and feel free to post your valuable comments and suggestions here. Thank you

which algorithm did you use?
The program doesn’t solve the sudoku, hence I didn’t use any known algorithm. The program first checks the horizontal rows for duplicate numbers, then the vertical rows and then the individual sub-matrices. Has anyone defined this procedure as an algorithm? Thank you for the comment
I like this program.I would like to share this program with my friends, will you please send this program to my email..