PHP：如何创建唯一的有序列表？

Question

This is for a game. I have an array with 52 elements in it. I want to be able to create a unique list of these elements each time, but don't want to use randomized because it runs the risk of having the first few and last elements be the same at the start or end of the sequence.

I'm thinking how can I approach this if not using a truly randomized list. So I thought, what about if I start off to seed the list with a randomized list, and then each time after that it does a unique method of ordering the list, so while it appears to be random it doesn't duplicate the first few and last elements.

So one method I'm considering is to start in the middle of the randomized list and go up one element and down one element to create the new order of the list. Then each time after that, do the same sort of shuffling for lack of a better term.

Are there other approaches to doing this that might be popular but I'm not considering?

I started to write this in PHP, but my code isn't working. Not sure what I'm doing wrong, so you can kindly comment on it if you feel this is a good approach for the ordering even though my PHP code isn't working. Thanks!

// First create an array of 52 elements, numbered 1…52.
for ($number=1; $number<=52; $number++)
    {
    $sequential_list[$number] = $number;
    }

print_r($sequential_list);

// Find the middle of $sequential_list

$middle = 26;

// Set the $middle as the first element in the new_list to seed it.
// Now go up one and down one from the $middle
    $new_list[1] = $sequential_list[$middle];
    $up = $middle;
    $down = $middle;
$index = 2; 

while ($index<=52)
    {
    $new_list[$index] = $sequential_list[$up++];
    echo "up is: " . $up . "\n";
    $new_list[$index++] = $sequential_list[$down--];
    }

print_r($new_list);

A simple example would be an array of 52 elements which are numbered 1 to 52. It would start in the middle, go up one and down one. So that 1 = 26, 2 = 27, 3 = 25, 4 = 28, 5 = 24, 6 = 29, 7 = 23, etc.

Answer 1

$middle = rand(5,47);//as not to get the first and last five elements int the same order

$first = array_slice($sequential_list, 0, $middle);
$second = array_slice($sequential_list, $middle);

shuffle($first);
shuffle($second);

$random_list = array_merge($second, $first);

For the next iteration you start again from the new random_list.