PROBLEM 1: MINI SUDOKU

 Write a C program that solves a mini sudoku puzzle.

  The program must:
   * prompt the user for the name of text file.
   * read the description of the puzzle from the file
   * solve the puzzle
   * print the solution on the screen

Rules of the game:

The game is played on a 6x6 board that has 6 2x3 rectangles.
The initial board configuration contains some numbers which
constrain the solution to the puzzle. The objective is to fill in the
empty squares with numbers from 1 to 6, such that:  
all numbers from 1 to 6 appear (without repetitions)
in all six 2x3 rectangles as well as all rows and all columns.

+------+-------+
|3 . . | . . . |
|. . 1 | 5 . . |
+------+-------+
|. 4 . | . 3 . |
|. 6 . | . 2 . |
+------+-------+
|. . 2 | 3 . . |
|. . . | . . 6 |
+------+-------+

 
Solution:
+------+-------+
|3 5 6 | 1 4 2 |
|4 2 1 | 5 6 3 |
+------+-------+
|2 4 5 | 6 3 1 |
|1 6 3 | 4 2 5 |
+------+-------+
|6 1 2 | 3 5 4 |
|5 3 4 | 2 1 6 |
+------+-------+

 
Format of the text file:
 
 * Six lines (int plain text format) 
 * Each line contains exactly 6 numbers
 * a number from 1 to 6 means that square has a fixed value
 * 0 means that square is empty and the program must find its correct value.

Sample file:
3 0 0 0 0 0
0 0 1 5 0 0
0 4 0 0 3 0
0 6 0 0 2 0
0 0 2 3 0 0 
0 0 0 0 0 6

Sample file:
2 0 0 0 0 1
0 1 0 0 2 0
0 0 6 1 0 0
0 0 5 2 0 0
0 4 0 0 6 0 
3 0 0 0 0 5

You can find more examples in almost any newspaper or on-line.
 
 


PROBLEM 2: TIC-TAC-TOE

* Write a C program that plays the game of Tic-Tac-Toe against the user.