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.

样例

X X X XX O O XX X O XX O X X

After capture all regions surrounded by 'X', the board should be:

X X X XX X X XX X X XX O X X 代码如下，这次用的java因为c++其实并没有看过多少，只了解一点C的。 思路就是从边界的‘O’开始搜索与其相连的‘O’，并标记， 直到所有边界上的‘O’都被搜索过，没有被标记的就是被包围的。 本来想用BFS的，但是刚写到方法名想到其实不用bfs就能搞定，递归的出口也很明显，于是。。

1 public class Solution { 2     /** 3      * @param board a 2D board containing 'X' and 'O' 4      * @return void 5      */ 6     int flag[][]= new int[1000][1000]; 7     int x = 0; 8     int y = 0; 9     public void surroundedRegions(char[][] board) {10         // Write your code here11         this.x = board.length;12         if(board.length == 0) return ;13         this.y = board[0].length;14         for(int i = 0; i
         
          =0 && j
          
           =0 && flag[i][j] == 0 && board[i][j] == 'O' ) {34             this.flag[i][j] = 1;35             bfs(board,i+1,j);36             bfs(board,i,j+1);37             bfs(board,i-1,j);38             bfs(board,i,j-1);39         }40     }41 }