Mathematical and Physical Journal
for High Schools
Issued by the MATFUND Foundation
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# Problem S. 29. (October 2007)

S. 29. Readers of our Journal might remember Problem I. 136. about the Sudoku game. The aim of this well-known puzzle is to fill in a 9×9 grid with digits between 1 and 9 so that each row, column and 3×3 subgrid contain only one instance of each digit.

Write a program that solves a partially completed Sudoku grid according to the following rules:

- if there is a unique solution, then the output should be the complete grid (that is, 9×9 digits, given in 9 rows),

- if the solution is not unique, then a possible solution should be displayed in 9 rows, while a warning Solution is not unique'' in the 10th row,

- if there is no solution, then simply display No solution''.

The name of the input text file is given as the first argument in the command line. This file contains 9 rows with given digits. Dots denote missing digits. The output should be written to the standard output.

You should submit the source code of the program (s29.pas, s29.cpp, ...), a short documentation of your solution (s29.txt, s29.pdf, ...) and the name and version number of the compiler (e.g., Free Pascal 2.0, Borland C++ 3.1, ...).

(10 pont)

Deadline expired on November 15, 2007.

Sorry, the solution is available only in Hungarian. Google translation

Megoldás. A versenyzők többsége visszalépéses kereséssel oldotta meg a feladatot.

Mintaként Fábián András (s29.pas) szegedi versenyző programját közöljük.

### Statistics:

 6 students sent a solution. 10 points: Fábián András, Godó Zita, Strenner Péter, Sztupovszki Szabolcs. 9 points: Szebeni Szilveszter. 2 points: 1 student.

Problems in Information Technology of KöMaL, October 2007