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  1. <?php
  2. test();
  3.  
  4. function joiner($a) { return join(', ', $a); }
  5. function test() {
  6. 	$test = ['a','b','c','d'];
  7. 	$N = 3;
  8.  
  9. 	$r = getSequenses( $N, $test);
  10. 	print_r( array_map( 'joiner', $r));
  11. }
  12.  
  13. function getSequenses( $N, $arr) {
  14. 	$L = count($arr);
  15. 	if( $L > 32) throw new Exception("Массив длиннее 32 элементов");
  16. 	$result = [];
  17.  
  18. 	for( $i=0; $i<pow( 2, $L); $i++) {
  19. 		if( $N != countBits( $i)) continue;
  20.  
  21. 		// get all permutations
  22. 		$set = array();
  23. 		$bits = $i;
  24. 		for( $j=0; $bits; $j++) {
  25. 			if( !($bits & 1)) {
  26. 				$bits = $bits >> 1;
  27. 				continue;
  28. 			}
  29. 			array_push( $set, $arr[ $j]);
  30. 			$bits = $bits >> 1;
  31. 		}
  32.  
  33. 		$result = array_merge( $result, permute( $set));
  34. 	}
  35.  
  36. 	return $result;
  37.  
  38. }
  39.  
  40. function permute( $items, $perms = array(), &$result = array()) {
  41.     if( empty( $items)) {
  42. 	    array_push( $result, $perms);
  43.     } else {
  44.         for( $i = count( $items) - 1; $i >= 0; --$i) {
  45.              $newitems = $items;
  46.              $newperms = $perms;
  47.              list($foo) = array_splice($newitems, $i, 1);
  48.              array_unshift($newperms, $foo);
  49.              permute( $newitems, $newperms, $result);
  50. 		}
  51. 	}
  52.  
  53. 	return $result;
  54. }
  55.  
  56. function countBits( $n) {
  57.     $count = 0;
  58.     while( $n) {
  59.         $count += ( $n & 1);
  60.         $n = $n >> 1;
  61.     }
  62.  
  63.     return $count;
  64. }
Success #stdin #stdout 0.04s 52480KB
comments (?)
stdin 
Standard input is empty
stdout 
Array
(
    [0] => a, b, c
    [1] => b, a, c
    [2] => a, c, b
    [3] => c, a, b
    [4] => b, c, a
    [5] => c, b, a
    [6] => a, b, d
    [7] => b, a, d
    [8] => a, d, b
    [9] => d, a, b
    [10] => b, d, a
    [11] => d, b, a
    [12] => a, c, d
    [13] => c, a, d
    [14] => a, d, c
    [15] => d, a, c
    [16] => c, d, a
    [17] => d, c, a
    [18] => b, c, d
    [19] => c, b, d
    [20] => b, d, c
    [21] => d, b, c
    [22] => c, d, b
    [23] => d, c, b
)
https://ideone.com/0XfUkI
language:
PHP (php 7.3.5)
created:
10 years ago
visibility:
public

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