PHP countNeighbors Examples

Example #1

File: part2.php Project: ultramega/adventofcode2015

function getLightState(array $grid, $r, $c)
{
    if (($r === 0 || $r === count($grid) - 1) && ($c === 0 || $c === count($grid[$r]) - 1)) {
        return 1;
    }
    $neighbors = countNeighbors($grid, $r, $c);
    if ($grid[$r][$c] === 1) {
        return $neighbors === 2 || $neighbors === 3 ? 1 : 0;
    }
    return $neighbors === 3 ? 1 : 0;
}

Example #2

File: part1.php Project: ultramega/adventofcode2015

    $n += get($grid, $r - 1, $c - 1);
    $n += get($grid, $r - 1, $c);
    $n += get($grid, $r - 1, $c + 1);
    $n += get($grid, $r, $c - 1);
    $n += get($grid, $r, $c + 1);
    $n += get($grid, $r + 1, $c - 1);
    $n += get($grid, $r + 1, $c);
    $n += get($grid, $r + 1, $c + 1);
    return $n;
}
function get(array $grid, $r, $c)
{
    return isset($grid[$r][$c]) ? $grid[$r][$c] : 0;
}
$num = 0;
for ($i = 0; $i < $steps; $i++) {
    $newGrid = array();
    $num = 0;
    foreach ($grid as $r => $row) {
        foreach ($row as $c => $cell) {
            $neighbors = countNeighbors($grid, $r, $c);
            if ($cell === 1) {
                $num += $newGrid[$r][$c] = $neighbors === 2 || $neighbors === 3 ? 1 : 0;
            } else {
                $num += $newGrid[$r][$c] = $neighbors === 3 ? 1 : 0;
            }
        }
    }
    $grid = $newGrid;
}
echo 'Answer: ' . $num . PHP_EOL;