11) Problem 11- Project Euler Solution in Java What is the greatest product of four adjacent numbers in the same direction (up, down, left, right, or diagonally) in the 20×20 grid? So, I basically went through every possible way we could do the multiplication in the 20X20 grid. However, the greatest product can be found found easily if I had done multiplication diagonally rather than attempt all the trials. But, anyway it was a good practice with 2-D arrays. public static void main(String[] args) throws IOException { FileReader ff = new FileReader("Grid File (20X20).txt"); Scanner in = new Scanner(ff); int[][] num = new int[20][20]; ArrayList<Integer> list = new ArrayList(); //reading the numbers into 2D array for(int i=0;i<20;i++){ ...