Creating a new sudoku puzzle

Question

I have a board of a solved sudoku and I'm trying to randomly replace some of the elements with 0 to make a new puzzle. How do I do it?

board = [[2, 1, 3, 4], 
         [3, 4, 1, 2], 
         [1, 2, 4, 3],  
         [4, 3, 2, 1]]

Answer 1

You can use random.sample to find n random coordinates to remove from the board. For example, the following will set 5 random cells to 0:

>>> import random
>>> empty_cells = random.sample([(i, j) for i in range(4) for j in range(4)], 5)
>>> for row, col in empty_cells:
...     board[row][col] = 0
... 
>>> board
[[2, 0, 3, 0], [3, 4, 0, 2], [1, 2, 0, 3], [4, 0, 2, 1]]