int k =0;  
20:          while(k<xIndex.size())  
21:          {  
22:            int x = xIndex[k];  
23:            int y = yIndex[k];     
24:            visited[x*row +y] =1;  
25:            if(IsInBoundary(x, y, row, col)) surranded = false;  
26:            if(x<row-1 && board[x+1][y] == ‘O‘ && !IsVisited((x+1)*row+y)) {xIndex.push_back(x+1); yIndex.push_back(y);}  
27:            if(y<col-1 && board[x][y+1] == ‘O‘ && !IsVisited(x*row+y+1)) {xIndex.push_back(x); yIndex.push_back(y+1);}  
28:            k++;  
29:          }