求一个数组，n个元素的不同组合(排列组合问题)

偏执的太偏执、 2022-06-14 00:07 238阅读 0赞

array('a1','b2','c3','d4','e5','x1','y1','z1');比如以上数组

我想要这个数组元素中三个元素的不同组合，例如下

array('a1','b2','c3');  
array('a1','b2','d4');  
array('a1','b2','e5');  
array('a1','b2','x1');  
array('a1','b2','y1');

方法一:最先想到的就是n次foreach循环，该方法简单粗暴

$data = array('a1','b2','c3','d4','e5','x1','y1','z1'); foreach ($data as $k_1 => $v_1) { foreach ($data as $k_2 => $v_2) { foreach ($data as $k_3 => $v_3) { if ($v_1 !== $v_2 && $v_1 !== $v_3 && $v_2 !== $v_3) { var_dump([$v_1,$v_2,$v_3]); } } } }

方法二:运用递归

<?php $arr = array('a','b','c','d'); $result = array(); $t = getCombinationToString($arr, 3); print_r($t); function getCombinationToString($arr, $m) { if ($m ==1) { return $arr; } $result = array(); $tmpArr = $arr; unset($tmpArr[0]); for($i=0;$i<count($arr);$i++) { $s = $arr[$i]; $ret = getCombinationToString(array_values($tmpArr), ($m-1)); foreach($ret as $row) { $result[] = $s . $row; } } return $result; } ?>

结果如下：

Array  
(  
    \[0\] => abc  
    \[1\] => abd  
    \[2\] => acc  
    \[3\] => acd  
    \[4\] => adc  
    \[5\] => add  
    \[6\] => bbc  
    \[7\] => bbd  
    \[8\] => bcc  
    \[9\] => bcd  
    \[10\] => bdc  
    \[11\] => bdd  
    \[12\] => cbc  
    \[13\] => cbd  
    \[14\] => ccc  
    \[15\] => ccd  
    \[16\] => cdc  
    \[17\] => cdd  
    \[18\] => dbc  
    \[19\] => dbd  
    \[20\] => dcc  
    \[21\] => dcd  
    \[22\] => ddc  
    \[23\] => ddd  
)

文章出处:https://segmentfault.com/q/1010000005748820?\_ea=890576