PHP查找数组的所有（有点）唯一组合
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【中文标题】PHP查找数组的所有（有点）唯一组合【英文标题】：PHP Find All (somewhat) Unique Combinations of an Array 【发布时间】：2013-04-25 00:03:48 【问题描述】：我整天都在看 php 数组排列/组合问题.. 仍然无法弄清楚：/
如果我有一个类似的数组：
20 //key being 0
20 //key being 1
22 //key being 2
24 //key being 3
我需要这样的组合：
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：
20, 22, 24
因为它不想重复 20 次……但这正是我所需要的！
这是我的代码。直接来自Php recursion to get all possibilities of strings
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) 行，没有运气
================
我已经查看过的问题与导致内存不足错误的 OR 不同！：
How can I get all permutations in PHP without sequential duplicates? Permutations - all possible sets of numbers Combinations, Dispositions and Permutations in PHP PHP array combinations Get all permutations of a PHP array? PHP: How to get all possible combinations of 1D array? Select only unique array values from this array Get all permutations of a PHP array? PHP: How to get all possible combinations of 1D array? Select only unique array values from this array How can I get all permutations in PHP without sequential duplicates? Algorithm to return all combinations of k elements from n Find combination(s) sum of element(s) in array whose sum equal to a given number Combinations, Dispositions and Permutations in PHP PHP array combinations Php recursion to get all possibilities of strings How to return permutations of an array in PHP? Permutations - all possible sets of numbers Subset-sum problem in PHP with mysql Find unique combinations of values from arrays filtering out any duplicate pairs Finding all the unique permutations of a string without generating duplicates Generate all unique permutations Subset sum for exactly k integers?我已经尝试了其中一些算法，其中包含 12 个项目，但最终内存不足。然而，我目前使用的算法并没有给我一个内存不足的错误....但是..我需要那些重复的！
【问题讨论】：
请给出输入数据和预期输出的正确示例。var_dump() 格式适合
我终于在 PHP 中找到了一个递归的东西——请看我的回答...
【参考方案1】：
如果您不介意使用几个全局变量，您可以在 PHP 中执行此操作（翻译自 javascript 中的 version）：
<?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 ) )
【讨论】：
这里还有一个梨包：pear.php.net/package/Math_Combinatorics【参考方案2】：pear 包 Math_Combinatorics 使这类问题变得相当容易。它需要的代码相对较少，简单明了，而且很容易阅读。
$ cat code/php/test.php
<?php
$input = array(20, 20, 22, 24);
require_once 'Math/Combinatorics.php';
$c = new Math_Combinatorics;
$combinations = $c->combinations($input, 3);
for ($i = 0; $i < count($combinations); $i++)
$vals = array_values($combinations[$i]);
$s = implode($vals, ", ");
print $s . "\n";
?>
$ php code/php/test.php
20, 20, 22
20, 20, 24
20, 22, 24
20, 22, 24
如果我必须把它打包成一个函数，我会做这样的事情。
function combinations($arr, $num_at_a_time)
include_once 'Math/Combinatorics.php';
if (count($arr) < $num_at_a_time)
$arr_count = count($arr);
trigger_error(
"Cannot take $arr_count elements $num_at_a_time "
."at a time.", E_USER_ERROR
);
$c = new Math_Combinatorics;
$combinations = $c->combinations($arr, $num_at_a_time);
$return = array();
for ($i = 0; $i < count($combinations); $i++)
$values = array_values($combinations[$i]);
$return[$i] = $values;
return $return;
这将返回一个数组数组。获取文本。 . .
<?php
include_once('combinations.php');
$input = array(20, 20, 22, 24);
$output = combinations($input, 3);
foreach ($output as $row)
print implode($row, ", ").PHP_EOL;
?>
20, 20, 22
20, 20, 24
20, 22, 24
20, 22, 24
【讨论】：
为什么要重新发明***？这可能是这里最好的答案，我已经下载了梨类并将其包含在我的项目中......谢谢【参考方案3】：为什么不只使用二进制？至少那么它简单且很容易理解每一行代码的作用是这样的吗？这是我在一个项目中为自己编写的一个函数，我认为它非常简洁！
function search_get_combos($array)
$bits = count($array); //bits of binary number equal to number of words in query;
//Convert decimal number to binary with set number of bits, and split into array
$dec = 1;
$binary = str_split(str_pad(decbin($dec), $bits, '0', STR_PAD_LEFT));
while($dec < pow(2, $bits))
//Each 'word' is linked to a bit of the binary number.
//Whenever the bit is '1' its added to the current term.
$curterm = "";
$i = 0;
while($i < ($bits))
if($binary[$i] == 1)
$curterm[] = $array[$i]." ";
$i++;
$terms[] = $curterm;
//Count up by 1
$dec++;
$binary = str_split(str_pad(decbin($dec), $bits, '0', STR_PAD_LEFT));
return $terms;
对于您的示例，此输出：
Array
(
[0] => Array
(
[0] => 24
)
[1] => Array
(
[0] => 22
)
[2] => Array
(
[0] => 22
[1] => 24
)
[3] => Array
(
[0] => 20
)
[4] => Array
(
[0] => 20
[1] => 24
)
[5] => Array
(
[0] => 20
[1] => 22
)
[6] => Array
(
[0] => 20
[1] => 22
[2] => 24
)
[7] => Array
(
[0] => 20
)
[8] => Array
(
[0] => 20
[1] => 24
)
[9] => Array
(
[0] => 20
[1] => 22
)
[10] => Array
(
[0] => 20
[1] => 22
[2] => 24
)
[11] => Array
(
[0] => 20
[1] => 20
)
[12] => Array
(
[0] => 20
[1] => 20
[2] => 24
)
[13] => Array
(
[0] => 20
[1] => 20
[2] => 22
)
[14] => Array
(
[0] => 20
[1] => 20
[2] => 22
[3] => 24
)
)
【讨论】：
【参考方案4】：想法很简单。假设你知道如何排列，那么如果你将这些排列保存在一个集合中，它就会变成一个组合。按定义设置会处理重复值。 Set 或 HashSet 的 Php 等价物是 SplObjectStorage，而 ArrayList 是 Array。重写应该不难。我有一个 Java 实现：
public static HashSet<ArrayList<Integer>> permuteWithoutDuplicate(ArrayList<Integer> input)
if(input.size()==1)
HashSet<ArrayList<Integer>> b=new HashSet<ArrayList<Integer>>();
b.add(input);
return b;
HashSet<ArrayList<Integer>>ret= new HashSet<ArrayList<Integer>>();
int len=input.size();
for(int i=0;i<len;i++)
Integer a = input.remove(i);
HashSet<ArrayList<Integer>>temp=permuteWithoutDuplicate(new ArrayList<Integer>(input));
for(ArrayList<Integer> t:temp)
t.add(a);
ret.addAll(temp);
input.add(i, a);
return ret;
【讨论】：
【参考方案5】：遇到了同样的问题，找到了一个不同的、按位更快的解决方案：
function bitprint($u)
$s = array();
for ($n=0; $u; $n++, $u >>= 1)
if ($u&1)
$s [] = $n;
return $s;
function bitcount($u)
for ($n=0; $u; $n++, $u = $u&($u-1));
return $n;
function comb($c,$n)
$s = array();
for ($u=0; $u<1<<$n; $u++)
if (bitcount($u) == $c)
$s [] = bitprint($u);
return $s;
这个生成从 0 到 n-1 的所有大小为 m 的整数组合，例如 m = 2, n = 3 并调用 comb(2, 3) 将产生：
0 1
0 2
1 2
它为您提供索引位置，因此很容易通过索引指向数组元素。
编辑： 输入 comb(30, 5) 失败。不知道为什么，有人知道吗？
【讨论】：
你说得对，这是从 javascript 翻译过来的，甚至 javascript 代码也会因为相同的输入而失败。 它有效，但 comb(30,5) 无效。我认为是因为输入错误，30太高了。【参考方案6】：使用 strrev 和 for/foreach 循环清理了 Adi Bradfield 的建议，并且只得到独特的结果。
function search_get_combos($array = array())
sort($array);
$terms = array();
for ($dec = 1; $dec < pow(2, count($array)); $dec++)
$curterm = array();
foreach (str_split(strrev(decbin($dec))) as $i => $bit)
if ($bit)
$curterm[] = $array[$i];
if (!in_array($curterm, $terms))
$terms[] = $curterm;
return $terms;
【讨论】：
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