php实现的生成排列算法示例

站长建站教程

2025-05-27 0 59

本文实例讲述了php实现的生成排列算法。分享给大家供大家参考，具体如下：

<?php

function perm($s, $n, $index)

{

if($n == 0)

{

return '';

}

else

{

$nIndex = count($index); //可用的字符串下标

$res = array();

foreach($index as $i => $v)

{

$tmp = $index;

unset($tmp[$i]); //去掉当前的前缀

/* 调试信息，便于理解

echo "len $n , cur $i , index:\\n";

var_dump($tmp);

*/

$ret = perm($s, $n-1, $tmp); //递归得到稍短的排列

if($ret != '')

{

foreach($ret as $r)

{

$res[] = $s[$v] . $r; //将稍短的排列逐个拼上当前的前缀

}

else

{

$res[] = $s[$v];

}

return $res;

}

function getPerm($s)

{

$n = strlen($s);

$index = range(0, $n-1);

//得到不同长度的排列

for($i=1; $i<=$n; $i++)

{

var_dump(perm($s, $i, $index));

}

getPerm('abcd');

?>

运行结果：

array(4) {
[0]=>
string(1) "a"
[1]=>
string(1) "b"
[2]=>
string(1) "c"
[3]=>
string(1) "d"
}
array(12) {
[0]=>
string(2) "ab"
[1]=>
string(2) "ac"
[2]=>
string(2) "ad"
[3]=>
string(2) "ba"
[4]=>
string(2) "bc"
[5]=>
string(2) "bd"
[6]=>
string(2) "ca"
[7]=>
string(2) "cb"
[8]=>
string(2) "cd"
[9]=>
string(2) "da"
[10]=>
string(2) "db"
[11]=>
string(2) "dc"
}
array(24) {
[0]=>
string(3) "abc"
[1]=>
string(3) "abd"
[2]=>
string(3) "acb"
[3]=>
string(3) "acd"
[4]=>
string(3) "adb"
[5]=>
string(3) "adc"
[6]=>
string(3) "bac"
[7]=>
string(3) "bad"
[8]=>
string(3) "bca"
[9]=>
string(3) "bcd"
[10]=>
string(3) "bda"
[11]=>
string(3) "bdc"
[12]=>
string(3) "cab"
[13]=>
string(3) "cad"
[14]=>
string(3) "cba"
[15]=>
string(3) "cbd"
[16]=>
string(3) "cda"
[17]=>
string(3) "cdb"
[18]=>
string(3) "dab"
[19]=>
string(3) "dac"
[20]=>
string(3) "dba"
[21]=>
string(3) "dbc"
[22]=>
string(3) "dca"
[23]=>
string(3) "dcb"
}
array(24) {
[0]=>
string(4) "abcd"
[1]=>
string(4) "abdc"
[2]=>
string(4) "acbd"
[3]=>
string(4) "acdb"
[4]=>
string(4) "adbc"
[5]=>
string(4) "adcb"
[6]=>
string(4) "bacd"
[7]=>
string(4) "badc"
[8]=>
string(4) "bcad"
[9]=>
string(4) "bcda"
[10]=>
string(4) "bdac"
[11]=>
string(4) "bdca"
[12]=>
string(4) "cabd"
[13]=>
string(4) "cadb"
[14]=>
string(4) "cbad"
[15]=>
string(4) "cbda"
[16]=>
string(4) "cdab"
[17]=>
string(4) "cdba"
[18]=>
string(4) "dabc"
[19]=>
string(4) "dacb"
[20]=>
string(4) "dbac"
[21]=>
string(4) "dbca"
[22]=>
string(4) "dcab"
[23]=>
string(4) "dcba"
}