Imagine a simplified version of the game Battleship played on a 2D grid. The grid represents the sea, and each cell can either be empty (.) or contain a part of a ship (X). Ships are placed horizontally or vertically, and there are no adjacent ships. Given a grid, count the number of battleships in it. Extra credit: can you make a layout generat…

battleship.php

<?php

function numberOfShips(array $ships): int
{
    $totalShips = 0;

    $rows = count($ships);
    $cols = count($ships[0]);

    for ($r = 0; $r < $rows; $r++)
    {
        for ($c = 0; $c < $cols; $c++)
        {
            if ($ships[$r][$c] !== 'X') continue;

            $checkUpShip = $r > 0 && $ships[$r-1][$c] == 'X';
            $checkLeftShip = $c > 0 && $ships[$r][$c-1] == 'X';

            if(!$checkUpShip && !$checkLeftShip)
            {
                $totalShips++;
            }
        }
    }

    return (int)$totalShips;
}

$ships = [
  ['X', 'X', '.', 'X'],
  ['.', '.', '.', 'X'],
  ['.', '.', '.', 'X'],
  ['.', '.', '.', '.'],
];
echo numberOfShips($ships) . PHP_EOL; // 2

$ships = [
  ['X', 'X', '.', 'X'],
  ['.', '.', '.', 'X'],
  ['X', '.', '.', 'X'],
  ['X', '.', '.', '.'],
];
echo numberOfShips($ships) . PHP_EOL; // 3

$ships = [
  ['X', '.', '.', '.'],
  ['X', '.', '.', '.'],
  ['.', 'X', 'X', 'X'],
  ['.', '.', '.', '.'],
];
echo numberOfShips($ships) . PHP_EOL; // 2