我怎样才能得到一个字的字符的所有唯一组合？ [英] How can I get all unique combinations of a word's characters?

问题描述

我知道如何 str_shuffle（）或洗牌的作品，但我不知道在这种情况下。

I understand how str_shuffle() or shuffle works but I don't know it in this case.

$word="tea";

我想呼应了所有独特的洗牌可能性（茶，TAE，ETA，吃，吃，AET）

I want to echo out all unique shuffling possibilities (tea, tae, eta, eat, ate, aet)

推荐答案

您需要制作的所有字符串的排列，方法是通过迭代的可能性，或使用类似下面这一个递归方法。请注意，对于一个中等大小的数组，这将变得非常大非常快。对于具有独特字符的字，可能的排列的数量是n！其中n是长度。对于六个字母组成的单词数组将有720项！这种方法是不是最有效的，但是这取决于你正在尝试做的，它应该工作正常。

You need to produce all of the permutations of the string, either by iterating through the possibilities, or using a recursive method like this one below. Note that for a moderately sized array this will grow very large very quickly. For a word with unique characters, the number of possible permutations is n! where n is the length. For a six-letter word the array will have 720 entries! This method is not the most efficient, but depending on what you are trying to do, it should work ok.

（来源：的http：// cogo.word press.com / 2008/01/08 /串置换，在PHP / ）

function permute($str) {
    /* If we only have a single character, return it */
    if (strlen($str) < 2) {
        return array($str);
    }

    /* Initialize the return value */
    $permutations = array();

    /* Copy the string except for the first character */
    $tail = substr($str, 1);

    /* Loop through the permutations of the substring created above */
    foreach (permute($tail) as $permutation) {
        /* Get the length of the current permutation */
        $length = strlen($permutation);

        /* Loop through the permutation and insert the first character of the original
        string between the two parts and store it in the result array */
        for ($i = 0; $i <= $length; $i++) {
            $permutations[] = substr($permutation, 0, $i) . $str[0] . substr($permutation, $i);
        }
    }

    /* Return the result */
    return $permutations;
}

请注意，这有点幼稚实施将不能正确处理重复字母（例如，种子，具有两个e`s）。如上文源指出，你可以使用下面的code。如果字包含相同字母的倍数，以消除重复：

Note that this somewhat naive implementation will not handle duplicate letters correctly (for example, 'seed', having two e`s). As indicated in the source above, you can use the following code to eliminate duplicates if the word contains multiple of the same letter:

$permutations = array_unique(permute($str));

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