How to implement diagonal reversal of a two-dimensional array in PHP?

You can achieve the diagonal reversal of a PHP 2D array with the following code.

function diagonalReverse($arr) {
    // 获取二维数组的行数和列数
    $rows = count($arr);
    $cols = count($arr[0]);

    // 创建一个新的二维数组用于存放对角线反转后的结果
    $result = array_fill(0, $cols, array_fill(0, $rows, 0));

    // 遍历原二维数组，将元素按照对角线反转的规则放入新的二维数组中
    for ($i = 0; $i < $rows; $i++) {
        for ($j = 0; $j < $cols; $j++) {
            $result[$j][$i] = $arr[$i][$j];
        }
    }

    return $result;
}

// 测试
$arr = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
];

$result = diagonalReverse($arr);

foreach ($result as $row) {
    echo implode(' ', $row) . PHP_EOL;
}

The code above achieves a diagonal flip by performing the operation on the input 2D array and then outputs the result.