如何返回数组的排列在PHP？ [英] How to return permutations of an array in PHP?

问题描述

我有取一维阵列并返回该数组中的元素的所有可能的排列的函数;

I have a function that take a one dimensional array and returns all the possible permutations of the elements within the array;

function array_2D_permute($items, $perms = array()) {
static $permuted_array = array();
    if (empty($items)) {
        $permuted_array[]=$perms;
        #print_r($new);
        #print join(' ', $perms) . "\n";
    }  else {
        for ($i = count($items) - 1; $i >= 0; --$i) {
             $newitems = $items;
             $newperms = $perms;
             list($foo) = array_splice($newitems, $i, 1);
             array_unshift($newperms, $foo);
             array_2D_permute($newitems, $newperms);
         }
         return $permuted_array;
    }
}

$arr1=array("Architecture","Mexico","Periodicals");
$result1=array_2D_permute($arr1);
print_r($result1);

$arr2=array("Apple","Boat","Cat");
$result2=array_2D_permute($arr2);
print_r($result2);

第一次调用函数时，它按预期工作，但它被称为第二次，它也包括从第一个数组元素。我想不通这是为什么。

The first time the function is called, it works as expected, however the second time it is called, it also includes elements from the first array. I can't figure out why this is.

鸭preciate的帮助。

Appreciate the help.

推荐答案

由于您使用的是静态$ permuted_array;

您必须使用

static $permuted_array;      // declare static var, if you don't want to use static property of variable, then why are you using this
$permuted_array = array();   // set its value to array()

使用

静态$ permuted_array =阵列（）; 不会将其值设置为阵列（）第一个循环之后

using static $permuted_array = array(); will not set its value to array() after first iteration

function array_2D_permute($items, $perms = array(), $isNew = false) {
static $permuted_array = array();

if($isNew) 
   $permuted_array = array();


    if (empty($items)) {
        $permuted_array[]=$perms;
        #print_r($new);
        #print join(' ', $perms) . "\n";
    }  else {
        for ($i = count($items) - 1; $i >= 0; --$i) {
             $newitems = $items;
             $newperms = $perms;
             list($foo) = array_splice($newitems, $i, 1);
             array_unshift($newperms, $foo);
             array_2D_permute($newitems, $newperms);
         }
         return $permuted_array;
    }
}

$arr1=array("Architecture","Mexico","Periodicals");
$result1=array_2D_permute($arr1, array(), true);      //
print_r($result1);

$arr2=array("Apple","Boat","Cat");
$result2=array_2D_permute($arr2, array(), true);     ///
print_r($result2);

一个参数被添加$是否新款。如果你想获得的结果为新的阵列发送正确的。

one more parameter is added $isNew. Send true if you want to get result for new array.

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