Finding adjacent elements in a 2d array and counting them.

Question

Im stumped on what to do for this part of my homework and could really use some help. I need to cycle through a given 2d array and find all similar elements that are adjacent to another and count that so for example

AA--B
AA--B
-AA--
----C

So the count would be 3 one for the As one for the Bs and one for the C, I just kinda need an idea where to start So far i have

public static int howManyOrganisms(char[][] image){
    int count = 0;
    for (int i = 0; i < image.length; i++) {
        for (int j = 0; j < image[i].length; j++) {
            if(image[i][j] != '-') {
                count++;

            }
            System.out.println();
        }
        return howManyOrganisms(image, count);
    }
}

I need help figuring out how to track the total number of elements that are within contact of one another (so left, right, down, up) being another similar element.

Answer 1

In each iteration, you can use your i,j variables to "navigate" the 2d plane and see if any interacting items are the same. In each iteration you would check the following indexes to see if they are the same:

• image[i-1][j] (one row up)
• image[i+1][j] (one row down)
• image[i][j-1] (one left)
• image[i][j+1] (one right)

Of course for all of these statements first you should check if +1/-1 is still within the size of your matrix, otherwise you will end up with out of bounds exception.