Minesweeper Number of Neighbouring Mines

Create a function that takes a list representation of a Minesweeper board, and returns another board where the value of each cell is the amount of its neighbouring mines.

Examples

The input may look like this:

[
  [0, 1, 0, 0],
  [0, 0, 1, 0],
  [0, 1, 0, 1],
  [1, 1, 0, 0]
]

The 0 represents an empty space . The 1 represents a mine.

You will have to replace each mine with a 9 and each empty space with the number of adjacent mines, the output will look like this:

[
  [1, 9, 2, 1],
  [2, 3, 9, 2],
  [3, 9, 4, 9],
  [9, 9, 3, 1]
]

Notes

• Since in the output the numbers 0-8 are used to determine the amount of adjacent mines, the number 9 will be used to identify the mines instead.