Sudoku

# -*- coding: cp1252 -*-

class CSudoku (object):
    __slots__ = ['__sol', '__fixed', '__size']
    def __init__ (self, size):
        self.__sol = [[0]*size for i in range(size)]
        self.__fixed = [[False]*size for i in range(size)]
        self.__size = size
    def fill (self, row, column, value):
        if row <= self.__size and row > 0 and column <= self.__size and column > 0 and value <= self.__size:
            self.__sol[row-1][column-1] = value
            self.__fixed[row-1][column-1] = True
        else:
            raise IndexError, "Invalid arguments."
    def found (self, row, column, value):
        f = False
        for i in range(self.__size):
            if value == self.__sol[row][i] or value == self.__sol[i][column]:
                return True
        r = (int(row/3))*3
        c = (int(column/3))*3
        if (self.__sol[r+0][c+0] == value or self.__sol[r+0][c+1] == value or
            self.__sol[r+0][c+2] == value or self.__sol[r+1][c+0] == value or
            self.__sol[r+1][c+1] == value or self.__sol[r+1][c+2] == value or
            self.__sol[r+2][c+0] == value or self.__sol[r+2][c+1] == value or
            self.__sol[r+2][c+2] == value):
            f = True
        return f
    def sudoku (self, row, column):
        if not self.__fixed[row][column]: # Si la posició no està fixada.
            for k in range(1, self.__size+1): # Provem de posar un nombre.
                found = self.found(row, column, k)
                if not found: # Si no es troba el nombre:
                    self.__sol[row][column] = k
                    if column == self.__size-1 and row != self.__size-1: # Arribem al final de la fila.
                        self.sudoku(row+1, 0)
                    elif column != self.__size-1:
                        self.sudoku(row, column+1)
                    else:
                        print self
                self.__sol[row][column] = 0 # No s'ha trobat solució, següent iteració.
        else:
            if column == self.__size-1 and row != self.__size-1: # Arribem al final de la fila.
                self.sudoku(row+1, 0)
            elif column != self.__size-1:
                self.sudoku(row, column+1)
            else:
                print self
    def __str__ (self):
        text = '|+---+---+---++---+---+---++---+---+---+|\n'
        for i in range(self.__size):
            text += '|| '
            for k in range(self.__size):
                if self.__sol[i][k] != 0:
                    text += str(self.__sol[i][k])
                else:
                    text += ' '
                text += ' |'
                if k in [2, 5, 8]:
                    text += '|'
                text += ' '
            text += '\n|+---+---+---++---+---+---++---+---+---+|\n'
            if i in [2, 5]:
                text += '|+---+---+---++---+---+---++---+---+---+|\n'
        return text

if __name__ == '__main__':
    x = CSudoku(9)
    ls = [[1,4,2], [1,6,3], [1,8,6], [1,9,5], [2,2,2], [2,3,7], [2,6,9], [3,6,5], [4,3,5], [5,1,7], [5,2,8], [5,8,9], [6,1,2], [6,3,3], [6,8,4], [7,1,3], [7,4,5], [7,5,7], [7,6,4], [7,7,8], [8,3,2], [8,6,6], [8,8,7], [8,9,9], [9,3,6], [9,6,2], [9,9,4]]
    for i in ls:
        x.fill(*i)
    print "Sudoku a solucionar:"
    print x
    print "Sudoku resolt:"
    x.sudoku(0, 0)