Need help with a method to randomly lay mines in a minesweeper game

So my Java minesweeper game is represented as a int[][] where -1 represents a mine. When I initialize m开发者_开发技巧y game I need to randomly place x amount of mines.

What is an elegant way of doing this? I was thinking of using an ArrayList with the coordinates of each cell, randomly selecting it, changing the state of the int[][] and then removing that Point. This would ensure that no point is selected twice.

Is there a more elegant way of doing this?

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I'd do it similarly, but slightly differently. Use the card-dealing algorithm.

Create an array of all the coordinates in your grid, in order. ([0,0], [0,1] .. [0,max], [1,0] .. [max, max]). Then "shuffle the deck" by iterating the list in order and swapping each element with a random element. Then select the first x elements in the list and place mines in those locations.

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I would generate random coordinates and check the board for an existing mine. If it exists skip it and generate new coordinates, if it doesn't place a mine.

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I assume the mine width is fixed?

If so then you could do it this way:

say you have a 4x4 mine grid.

Convert a decimal into binary, so for a 4bit the range would be:

2^4 = 16 => Range is 0...15

Then simply call this function for each grid "row":

1,16,0,3

would transform to:

0001
1111
0000
0011

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This is in python. But it prints (x, y) coordinates of mines. Result is sorted, but it doesn't matter.

from random import sample
import sys

def randomSquares(n, m, mines):
  return sorted([ (mine % m, mine // n) for mine in sample(xrange(n * m), mines)])

if __name__ == '__main__':

  print randomSquares(int(sys.argv[1]), int(sys.argv[2]), int(sys.argv[3]))