生成长度为4的字符串,字符包括abcdefg,怎么样得到所有的组合?
把所有的可能存放到一个数组中,程序怎么实现。
可以重复比如aaaa,最好PHP实现的
回复内容:
把所有的可能存放到一个数组中,程序怎么实现。
可以重复比如aaaa,最好PHP实现的
python
<code>import itertools print list(itertools.permutations(["a","b","c","d","e","f","g"],4)) </code>
php
可以尝试这个:
http://www.honglei.net/?p=167
要考虑aaaa这样的存在吗?其实可以考虑给他们编码,假设abcdefg分别对应0123456,那么所有的情况就是:
0000(也就是0)~6666所有的数啦.
ps:7进制
直接上代码,四个for循环,简单暴力快速
<code><?php $dic = "abcdefg"; $list =array();//存放所有结果集 for($i=0;$i<7;$i++) for($j=0;$j<7;$j++) for($k=0;$k<7;$k++) for($l=0;$l<7;$l++){ $list[] = $dic[$i].$dic[$j].$dic[$k].$dic[$l]; } print_r($list); </code></code>
<code>function dfs($pre, $chars, $arr, $lenArr) { if(!empty($pre) && in_array(strlen($pre), $lenArr)){ $arr[] = $pre; } if(!empty($chars)) { foreach ($chars as $char) { $tempChars = array(); foreach ($chars as $c) { if ($c !== $char) { $tempChars[] = $c; } } $arr = $this->dfs($pre.$char, $tempChars, $arr, $lenArr); } } return $arr; } function get_combine() { $chars = array('a', 'b', 'c', 'd', 'e', 'f', 'g'); $combineArray = array(); $combineArray = $this->dfs('', $chars, $combineArray, array(4)); echo count($combineArray).'<br>'; var_dump($combineArray); }</code>

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