PHP查找数组的所有（某种程度上）唯一组合

小编典典

PHP查找数组的所有（某种程度上）唯一组合

algorithm

我整天都在看PHP数组排列/组合问题..仍然不知道：/

如果我有一个像这样的数组：

20 //key being 0    
20 //key being 1    
22 //key being 2    
24 //key being 3

我需要类似的组合：

20, 20, 22 //keys being 0 1 2    
20, 20, 24 //keys being 0 1 3    
20, 22, 24 //keys being 0 2 3
20, 22, 24 //keys being 1 2 3

我目前拥有的代码给我：

20, 22, 24

因为它不想重复20 …但这就是我所需要的！

这是我的代码。它直接来自Php递归来获取字符串的所有可能性

function getCombinations($base,$n){

$baselen = count($base);
if($baselen == 0){
    return;
}
    if($n == 1){
        $return = array();
        foreach($base as $b){
            $return[] = array($b);
        }
        return $return;
    }else{
        //get one level lower combinations
        $oneLevelLower = getCombinations($base,$n-1);

        //for every one level lower combinations add one element to them that the last element of a combination is preceeded by the element which follows it in base array if there is none, does not add
        $newCombs = array();

        foreach($oneLevelLower as $oll){

            $lastEl = $oll[$n-2];
            $found = false;
            foreach($base as  $key => $b){
                if($b == $lastEl){
                    $found = true;
                    continue;
                    //last element found

                }
                if($found == true){
                        //add to combinations with last element
                        if($key < $baselen){

                            $tmp = $oll;
                            $newCombination = array_slice($tmp,0);
                            $newCombination[]=$b;
                            $newCombs[] = array_slice($newCombination,0);
                        }

                }
            }

        }

    }

    return $newCombs;


}

我一直在玩($b == $lastEl)线，没有运气

===============

我用12个项目的数组尝试了其中的一些算法，最终耗尽了内存。但是，我当前正在使用的算法不会给我带来内存不足的错误……但是……我需要那些重复项！

阅读 297

2020-07-28

共1个答案

小编典典

如果您不介意使用几个全局变量，则可以在PHP中执行此操作）：

<?PHP
$result = array(); 
$combination = array();

function combinations(array $myArray, $choose) {
  global $result, $combination;

  $n = count($myArray);

  function inner ($start, $choose_, $arr, $n) {
    global $result, $combination;

    if ($choose_ == 0) array_push($result,$combination);
    else for ($i = $start; $i <= $n - $choose_; ++$i) {
           array_push($combination, $arr[$i]);
           inner($i + 1, $choose_ - 1, $arr, $n);
           array_pop($combination);
         }
  }
  inner(0, $choose, $myArray, $n);
  return $result;
}

print_r(combinations(array(20,20,22,24), 3));
?>

输出：

Array ( [0] => Array ( [0] => 20 
                       [1] => 20 
                       [2] => 22 ) 
        [1] => Array ( [0] => 20 
                       [1] => 20 
                       [2] => 24 ) 
        [2] => Array ( [0] => 20 
                       [1] => 22 
                       [2] => 24 ) 
        [3] => Array ( [0] => 20 
                       [1] => 22 
                       [2] => 24 ) )

2020-07-28