Finding All Possible Combinations of Array

[pureDesi]

I have an array, let's say it's values are ['A', 'B', 'C', 'D']. I want to list out all the possible combinations that can be achieved using these values so it would display something similar to

 

A

B

C

D

AB

BA

BC

BD

CA

CB

CD

DA

DB

DC

ABC

ABA

ABD

....

So on and so forth.

I've been working on it for some time and can't even come up with an algorithm, can anyone please assist me?

Thanks

[Psycho]

It's not pretty, but it works.

<?php

function notLast() {

  global $tempArray, $values;

  $iterations = count($values);

  $testArray = array_reverse($tempArray);

  foreach ($testArray as $key => $value) {
    if ($value != ($iterations-1) ) {
      $testArray[$key]++;
      for ($i=$key-1; $i>=0; $i--) {
        $testArray[$i] = $testArray[$i+1] + 1;
      }
      $tempArray = array_reverse($testArray);

      return true;
    }
    $iterations--;
  }

  return false;

}

$values = array ( 'A', 'B', 'C', 'D');

$results = array();

for ($parts = 1; $parts<=count($values); $parts++) {

  $tempArray = array();

  for ($i=0; $i<$parts; $i++) {
    $tempArray[$i] = $i;
  }

  do {

    $value="";
    foreach ($tempArray as $index) {
      $value = $value . $values[$index];
    }
    $results[] = $value;

  } while (notLast());

}


echo "<pre>";
print_r($results);
echo "</pre>";

?>

[btherl]

Try this on for size.. it doesn't generate them in the order you expect though.

 

function make_list($array, $length) {
  return make_list_rec('', $array, $length);
}

function make_list_rec($prefix, $array, $length) {
  $ret = array();
  $append = array();

  foreach ($array as $a) {
    $ret[] = "$prefix$a\n";
    if ($length === 1) continue;

    # Recurse
    $new_length = $length - 1;
    $new_prefix = $prefix . $a;
    $append = array_merge($append, make_list_rec($new_prefix, $array, $new_length));
  }

  return array_merge($ret, $append);
}

$array = array('a', 'b', 'c');
var_dump(make_list($array, 3));