Practice/Microsoft/Leetcode 529. Minesweeper

Leetcode 529. Minesweeper

CodingMust

Problem

You are implementing the click behavior for a mine-sweeper style game. Given a 2D character grid representing the game board and a click position, simulate what happens after the click.

The board uses these characters:

• 'M' represents an unrevealed mine
• 'E' represents an unrevealed empty square
• 'B' represents a revealed blank square (no adjacent mines)
• Digits '1' to '8' represent revealed squares showing the count of adjacent mines
• 'X' represents a revealed mine

When a square is clicked:

1. If it contains a mine ('M'), reveal it by changing it to 'X'. The game ends here.

2. If it's an empty square ('E'):

   • Count how many mines are in the 8 adjacent cells (horizontal, vertical, and diagonal neighbors)
   • If the count is greater than 0, change the cell to that digit (as a string)
   • If the count is 0, change the cell to 'B' and recursively reveal all 8 adjacent unrevealed empty squares

3. If the square is already revealed (not 'E' or 'M'), do nothing

Return the modified board after processing the click.

Requirements

1. Modify the board in-place based on the click position
2. If a mine is clicked, only that mine is revealed
3. If an empty cell with adjacent mines is clicked, show the count
4. If an empty cell with no adjacent mines is clicked, recursively reveal all connected empty regions
5. Already revealed cells should not be processed again

Constraints

• 1 <= board.length, board[i].length <= 50
• board[i][j] is one of: 'M', 'E', 'B', or a digit '1'-'8'
• click is a valid position within the board bounds
• click will always point to an unrevealed cell ('M' or 'E')

Examples

Example 1:

` Input: board = [['E', 'E', 'E', 'E', 'E'], ['E', 'E', 'M', 'E', 'E'], ['E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E']] click = [1, 2]

Output: [['E', 'E', 'E', 'E', 'E'], ['E', 'E', 'X', 'E', 'E'], ['E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E']]

Explanation: Clicking on a mine reveals it as 'X'. `

Example 2:

` Input: board = [['E', 'E', 'E', 'E', 'E'], ['E', 'E', 'M', 'E', 'E'], ['E', 'E', 'E', 'E', 'E'], ['E', 'E', 'E', 'E', 'E']] click = [3, 0]

Output: [['B', '1', 'E', '1', 'B'], ['B', '1', 'M', '1', 'B'], ['B', '1', '1', '1', 'B'], ['B', 'B', 'B', 'B', 'B']]

Explanation: Clicking on a cell with no adjacent mines triggers a flood-fill that recursively reveals all safe connected cells. Cells adjacent to the mine show their mine count. `