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  1. <?php
  2.  
  3. error_reporting(-1);
  4.  
  5. $elements = [1, 2, 3];
  6.  
  7. function factorial($n){
  8. 	if($n <= 1){
  9. 		return 1;
  10. 	} else {
  11. 		return $n * factorial($n - 1);
  12. 	}
  13. }
  14.  
  15. function getCombinations($elements){
  16. 	//print_r($elements);
  17. 	if(count($elements) == 1){
  18. 		return [$elements];
  19. 	}
  20. 	$result = [];
  21. 	foreach($elements as $key => $element){
  22. 		$first = $element;
  23. 		$firstKey = $key;
  24. 		unset($elements[$key]);
  25. 		$combinations = getCombinations($elements);
  26. 		$elements[] = $first;
  27. 		print_r($elements);
  28. 		foreach($combinations as &$combination){
  29. 			array_unshift($combination, $first);
  30. 			$result[] = $combination;
  31. 		}
  32.  
  33. 	}
  34. 	return $result;
  35. }
  36.  
  37. $result = getCombinations($elements);
  38. //print_r($result);
Success #stdin #stdout 0.02s 26216KB
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Array
(
    [2] => 3
    [3] => 2
)
Array
(
    [3] => 2
    [4] => 3
)
Array
(
    [1] => 2
    [2] => 3
    [3] => 1
)
Array
(
    [3] => 1
    [4] => 3
)
Array
(
    [4] => 3
    [5] => 1
)
Array
(
    [2] => 3
    [3] => 1
    [4] => 2
)
Array
(
    [4] => 2
    [5] => 1
)
Array
(
    [5] => 1
    [6] => 2
)
Array
(
    [3] => 1
    [4] => 2
    [5] => 3
)
https://ideone.com/h9J4W5
language:
PHP (php 7.3.5)
created:
2 years ago
visibility:
public

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