130. Surrounded Regions
Medium
30 Points
Array
Depth-First Search
Breadth-First Search
Union Find
Matrix
You are given an m x n matrix board containing letters 'X' and 'O', capture regions that are surrounded:
To capture a surrounded region, replace all 'O's with 'X's in-place within the original board. You do not need to return anything.
Examples
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"]]
Explanation:
In the above diagram, the bottom region is not captured because it is on the edge of the board and cannot be surrounded.
Example 2
Input: board = [["X"]]
Output: [["X"]]
Constraints
m == board.lengthn == board[i].length1 <= m, n <= 200board[i][j] is 'X' or 'O'.
130. Surrounded Regions
Medium
30 Points
Array
Depth-First Search
Breadth-First Search
Union Find
Matrix
You are given an m x n matrix board containing letters 'X' and 'O', capture regions that are surrounded:
To capture a surrounded region, replace all 'O's with 'X's in-place within the original board. You do not need to return anything.
Examples
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"]]
Explanation:
In the above diagram, the bottom region is not captured because it is on the edge of the board and cannot be surrounded.
Example 2
Input: board = [["X"]]
Output: [["X"]]
Constraints
m == board.lengthn == board[i].length1 <= m, n <= 200board[i][j] is 'X' or 'O'.