#1859Medium· asked at 13 companies
Surrounded Regions
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What we know
Example 1
Input: board = [["X","X","X","X"],["X","O","O","X"],["X","X","O","X"],["X","O","X","X"]] Output: [["X","X","X","X"],["X","X","X","X"],["X","X","X","X"],["X","O","X","X"]]
The bottom 'O' touches the border, so it stays.
Example 2
Input: board = [["X"]] Output: [["X"]]
Constraints
- •
m == board.length - •
n == board[i].length - •
1 <= m, n <= 200 - •
board[i][j]is 'X' or 'O'.