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  1. <?php
  2.  
  3. function Combinations($arr,$n){
  4.  
  5. 	if(count($arr) === 0) return;
  6.     if($n === 1){
  7.         $out = [];
  8.         foreach($arr as $b){
  9.             $out[] = [$b];
  10.         }
  11.         return $out;
  12.     }else{
  13.  
  14.         $base = Combinations($arr,$n-1);
  15. 		$out = [];
  16.  
  17.         foreach($base as $val){
  18.  
  19.             $last = $val[$n-2];
  20.             $found = false;
  21.             foreach($arr as $key => $value){
  22.             	 if($found === true){
  23.                         if($key < count($arr)){
  24.  
  25.                             $new = array_slice($val,0);
  26.                             $new[]=$value;
  27.                             $out[] = array_slice($new,0);
  28.                         }
  29.                         continue;
  30.                 }
  31.                 if($value === $last)
  32.                     $found = true;
  33.             }
  34.  
  35.         }
  36.  
  37.     }
  38.  
  39.     return $out;
  40.  
  41.  
  42. }
  43. $b= Combinations(array(1,2,3,4),4);
  44. $b[]= Combinations(array(1,2,3,4),3);
  45. $b[]= Combinations(array(1,2,3,4),2);
  46. print_r($b);
Success #stdin #stdout 0.01s 20520KB
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Array
(
    [0] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
            [3] => 4
        )

    [1] => Array
        (
            [0] => Array
                (
                    [0] => 1
                    [1] => 2
                    [2] => 3
                )

            [1] => Array
                (
                    [0] => 1
                    [1] => 2
                    [2] => 4
                )

            [2] => Array
                (
                    [0] => 1
                    [1] => 3
                    [2] => 4
                )

            [3] => Array
                (
                    [0] => 2
                    [1] => 3
                    [2] => 4
                )

        )

    [2] => Array
        (
            [0] => Array
                (
                    [0] => 1
                    [1] => 2
                )

            [1] => Array
                (
                    [0] => 1
                    [1] => 3
                )

            [2] => Array
                (
                    [0] => 1
                    [1] => 4
                )

            [3] => Array
                (
                    [0] => 2
                    [1] => 3
                )

            [4] => Array
                (
                    [0] => 2
                    [1] => 4
                )

            [5] => Array
                (
                    [0] => 3
                    [1] => 4
                )

        )

)
https://ideone.com/Mn2niT
language:
PHP (php 7.3.5)
created:
10 years ago
visibility:
public

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