Transform a number of islands into a number of countries solution in Javascript

Question

The original problem says that it should be counted the number of islands (connected entities of 1 into a sea of 0).

For example:

0001
1001
0110 

should return 3 becasue there are 3 islands.

I managed to get a solution to this:

function countIslands(A) {
    const row = A.length;
    const col = A[0].length;
    
    const search = (row, col, A) => {
        if(row < 0 || col < 0 || row > A.length - 1 || col > A[row].length - 1 || A[row][col] === 0) {
            return;
        }
        A[row][col] = 0;
        search(row-1,col,A);
        search(row,col-1,A);
        search(row+1,col,A);
        search(row,col+1,A);
    }
    let count = 0;
    A.forEach((row, index) => {
        row.forEach((value, indexI) => {
            if(value === 1) {
                search(index, indexI, A);
                count++;
            }
        })
    })
    return count;
}

it works fine. But is it a way to change it (ideally not a lot of changes) to make it able to count countries?

For example:

1122
1223
5521

should return 5 because there are 5 entities in the matrix.

Answer 1

You could hand over the actual value and look only for adjacent same values.

I add some visualation for the found islands/countries.

function countIslands(A) {
    const row = A.length;
    const col = A[0].length;

    const search = (row, col, A, value) => {
        if (row < 0 || col < 0 || row >= A.length || col >= A[row].length || A[row][col] !== value) {
            return;
        }
        A[row][col] = 0;
        search(row - 1, col, A, value);
        search(row, col - 1, A, value);
        search(row + 1, col, A, value);
        search(row, col + 1, A, value);
    }
    let count = 0;
    A.forEach((row, index) => {
        row.forEach((value, indexI) => {
            if (value !== 0) {

                A.forEach(a => console.log(...a));
                console.log('');

                search(index, indexI, A, value);
                count++;
            }
        })
    })
    A.forEach(a => console.log(...a))
    return count;
}

console.log(countIslands([[1, 1, 2, 2], [1, 2, 2, 3], [5, 5, 2, 1]]));

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