[LeetCode] Surrounded Regions

Given a 2D board containing 'X' and 'O', capture all regions surrounded by 'X'.

A region is captured by flipping all 'O's into 'X's in that surrounded region .

For example,

X X X X
X O O X
X X O X
X O X X
After running your function, the board should be:

X X X X
X X X X
X X X X
X O X X

[Solution].java

public class Solution {
    public void solve(char[][] board) {
        // Start typing your Java solution below
        // DO NOT write main() function
        if(board == null || board.length < 1 || board[0].length < 1) return;
        findLive(board);
        for(int i = 0; i < board.length; i++){
            for(int j = 0; j < board[0].length; j++){
        		if(board[i][j] == 'O') board[i][j] = 'X';
        		else if(board[i][j] == 'F') board[i][j] = 'O';
        	}
        }
    }

    public void findLive(char[][] board){
    	for(int colum = 0; colum < board[0].length; colum++) search(0, colum, board);
    	for(int row = 1; row < board.length - 1; row++) search(row, board[0].length - 1, board);
    	for(int colum = 1; colum < board[0].length; colum++) search(board.length - 1, colum, board);
    	for(int row = 1; row < board.length; row++) search(row, 0, board);
    }

    public void search(int row, int colum, char[][] board){
    	if(row < 0 || row >= board.length || colum < 0 || colum >= board[0].length
    		||board[row][colum] != 'O') return;
    	board[row][colum] = 'F';
    	search(row - 1, colum, board);
    	search(row + 1, colum, board);
    	search(row, colum - 1, board);
    	search(row, colum + 1, board);
    }
}