class Result {

    /*
     * Complete the 'bomberMan' function below.
     *
     * The function is expected to return a STRING_ARRAY.
     * The function accepts following parameters:
     *  1. INTEGER n
     *  2. STRING_ARRAY grid
     */

    public static List<String> bomberMan(int n, List<String> grid) {
        // Write your code here
        if(n == 1) return grid ;
        
        int row = grid.size() ;
        int col = grid.get(0).length() ;
        if(n%2 == 0)
        {
            return createZeroGrid(row, col);
        }
        
         // For odd values of n greater than 1, we simulate explosions
        // There are only two explosion patterns:
        // - one that occurs at time = 3 (and every 4 seconds after that)
        // - another that occurs at time = 5 (and every 4 seconds after that)
        
        List<String> after3 = afterExplosion(grid, row, col);
        List<String> after5 = afterExplosion(after3, row, col) ;
        
        if(n % 4 == 3)
        {
            return after3 ;
        }else{
            return after5 ;
        }
        

    }
    
    public static List<String> createZeroGrid(int row , int col)
    {
        List<String> result = new ArrayList<>();
        String s = "O".repeat(col);
        for(int i=0 ; i < row ; i++)
        {
            result.add(s);
        }
        return result ;
    }
    
    public static List<String> afterExplosion(List<String> grid , int row , int col)
    {
        char[][] resultCharArr = new char[row][col];
        for (int i = 0; i < row; i++) {
            Arrays.fill(resultCharArr[i],'O');
        }
        
        for (int i = 0; i < row; i++) {
            for (int j = 0; j < col ; j++) {
                if(grid.get(i).charAt(j) == 'O' )//if it's a bomb
                {
                    //blast that index and i+1,j and  i-1,j
                    // and i,j+1 and i,j-1 
                    // total 5 blast from 1 bomb 
                    resultCharArr[i][j] = '.';
                    
                    if(i > 0) resultCharArr[i-1][j] = '.';
                    if(i < row -1) resultCharArr[i+1][j] = '.';
                    
                    if(j > 0) resultCharArr[i][j-1] = '.';
                    if(j < col-1) resultCharArr[i][j+1] = '.';
                }
            }
        }
        
        // Convert the 2D char grid back into a list of strings
        List<String> result = new ArrayList<>();
        for(char[] rowOFchar:resultCharArr)
        {
               result.add(new String(rowOFchar));
        }
        
        return result ;
    }

}