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  1. <?php
  2.  
  3. error_reporting(-1);
  4.  
  5. $array = [1, 2, 3, 4];
  6.  
  7. function getFactorial($array){
  8. 	$factorial = 1;
  9. 	for($n = 1; $n<=count($array); $n++){
  10. 		$factorial *= $n;
  11. 	}
  12. 	return $factorial;
  13. }
  14.  
  15. $factorial = getFactorial($array);
  16.  
  17. function getCombinations($array){
  18. 	$output = [];
  19. 	if(count($array) == 2){
  20. 		$iterations = 2;
  21. 	} else {
  22. 		$iterations = count($array) * 2;
  23. 		$halfIterations = $iterations / 2;
  24. 	}
  25. 	while($iterations > 0){
  26. 		$combination = [];
  27. 		foreach($array as $key => $value){
  28. 			$firstKey = array_key_first($array);
  29. 			if($key == array_key_last($array)){
  30. 				$combination[$key] = $array[$firstKey];
  31. 			} else {
  32. 				$combination[$key] = next($array);
  33. 			}
  34. 		}
  35. 		if($iterations <= $halfIterations){
  36. 			krsort($combination);
  37. 		}
  38. 		$array = $combination;
  39. 		$output[] = $combination;
  40. 		$iterations--;
  41. 	}
  42. 	return $output;
  43. }
  44.  
  45. function Main($array){
  46. 	$str = "";
  47. 	$count = (count($array) - 1);
  48. 	if(count($array) == 1){
  49. 		return $array;
  50. 	} else {
  51. 		for($n = 0; $n <= $count; $n++){
  52. 			$cutElement = $array[$n];
  53. 			unset($array[$n]);
  54. 			$combinations = getCombinations($array, $factorial);
  55. 			foreach($combinations as $key => $value){
  56. 				array_unshift($combinations[$key], $cutElement);
  57. 				$str .= implode(" ", $combinations[$key]);
  58. 				$str .= "\n";
  59. 			}
  60. 			$array[$n] = $cutElement;
  61. 		}
  62. 	}
  63. 	return $str;
  64. }
  65.  
  66. $res = Main($array);
  67. echo $res;
Success #stdin #stdout #stderr 0.02s 26412KB
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stdin
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Standard input is empty
stdout
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1 3 4 2
1 4 2 3
1 2 3 4
1 2 4 3
1 4 3 2
1 3 2 4
2 4 1 3
2 1 3 4
2 3 4 1
2 1 4 3
2 4 3 1
2 3 1 4
3 1 2 4
3 2 4 1
3 4 1 2
3 1 4 2
3 4 2 1
3 2 1 4
4 2 3 1
4 3 1 2
4 1 2 3
4 1 3 2
4 3 2 1
4 2 1 3
stderr
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PHP Notice:  Undefined variable: factorial in /home/16wb01/prog.php on line 54
PHP Notice:  Undefined variable: factorial in /home/16wb01/prog.php on line 54
PHP Notice:  Undefined variable: factorial in /home/16wb01/prog.php on line 54
PHP Notice:  Undefined variable: factorial in /home/16wb01/prog.php on line 54
https://ideone.com/SnepM5
language:
PHP (php 7.3.5)
created:
2 years ago
visibility:
public

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