Generate 2D Minesweeper Grid

Problem Overview

You are tasked with building a minesweeper board. Given the number of rows rows, the number of columns cols, and a mine count n, your job is to place exactly n mines on distinct, randomly chosen cells of a rows x cols grid. Return (or print) the resulting 2D array.

This is not an object-oriented design question. The core algorithm is concise, so interviewers typically focus on code quality: minimizing variables, avoiding redundant data structures, and keeping control flow simple. The main challenge is selecting n distinct random cells cleanly.

Assume the following:

• 0 <= n <= rows * cols, so the request is always satisfiable.
• A mine cell is represented by 1 (or '*') and an empty cell by 0 (or '.').
• Any placement that puts exactly n mines on distinct cells is acceptable; the output is random.

Clarifications Worth Asking

• Is n guaranteed to be at most rows * cols? If not, should we cap it or reject the input?
• Should every valid board be equally likely, or is any correct placement of n distinct mines sufficient? Uniformity affects which approach is cleanest.
• What characters should be used for mines and empty cells in the printed grid?

Examples

Since the output is random, the following are just possible valid boards for illustration.

Example 1

Input:
rows = 3, cols = 3, n = 2
One possible output:

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

Explanation: Two mines are placed at distinct cells (0,1) and (2,0); all other cells are empty. Any arrangement with exactly two mines is valid.

Example 2

Input:
rows = 2, cols = 4, n = 3
One possible output:

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

Explanation: Three mines occupy distinct cells; the remaining cells are empty. The specific positions are random.

Constraints

• 0 <= n <= rows * cols
• The grid dimensions rows and cols are positive integers.
• The function signature is generate_grid(rows: int, cols: int, n: int) -> list[list[int]].
• The returned grid must contain exactly n mines (marked as 1) and rows * cols - n empty cells (marked as 0).
• Any valid placement is acceptable; uniform distribution is not required unless specified.