BattleshipCount.js

function countShips(B) {
    const result = [0, 0, 0];
    const map = B.map(row=>row.split(''));
    const n = map.length;
    const m = map[0].length;

    for (let row = 0; row < n; row++) {
        for (let col = 0; col < m; col++) {
            if (map[row][col] === '#') {
                map[row][col] = '.';

                const count = getSizeOfShip(map, row, col);
                if (count <= 3) {
                    result[count - 1]++;
                }
            }
        }
    }
    return result;
}

function isShipCell(map, row, col) {
    return row >= 0 && row < map.length && col >= 0 && col < map[0].length && map[row][col] === '#';
}

function getSizeOfShip(map, row, col) {
    const dirs = [[0, 1], [0, -1], [1, 0], [-1, 0]];
    const queue = [[row, col]];
    let sizeOfShip = 1;

    for (let i = 0; i < queue.length; i++) {
        const [currentRow,currentCol] = queue[i];

        for (let j = 0; j < dirs.length; j++) {

            const [dx,dy] = dirs[j]
            const x = currentRow + dx;
            const y = currentCol + dy;

            if (isShipCell(map, x, y)) {
                map[x][y] = '.';
                sizeOfShip++;
                queue.push([x, y]);
            }

        }
    }

    return sizeOfShip;
}

const B1 = [".##.#", "#.#..", "#...#", "#.##."];
console.log(countShips(B1).join(','));

const B2 = [".#..#", "##..#", "...#."];
console.log(countShips(B2).join(','));

const B3 = ["##.", "#.#", ".##"];
console.log(countShips(B3).join(','));

const B4 = ["...", "...", "..."];
console.log(countShips(B4).join(','));