PHP列出所有可能的具有特定数字的6位数字[重复]

Question

This question already has an answer here:

• Algorithm to get all possible string combinations from array up to certain length 12 answers

How could I generate every possible number of a given amount of digits and using specific digits?

So basically, I would like to have a 6 digit number for example using only the numbers ['1','2','3']. I've tried a few methods of recursion, however, I can't get it to work correctly due to my other complication, which is adding a separator of "|" in between each 2 digits. So the list would be like so:

11|11|11
11|11|12
11|11|13
11|11|21
11|11|22
11|11|23

etc.. Would be appreciated if someone could point me in the right direction. Also a way of dumping each of the combinations into my MySQL database would be great.

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Answer 1

Here is a much updated answer (originally updated from this answer]1) to your question:

function findPermutations($arr, $arrLen, $size, $perArr = array(), $pos = 0, &$found = array()) {
   if ($size==$pos) { //if $pos reach $size then we have found one permutation
      $found[] = vsprintf("%s%s|%s%s|%s%s", $perArr);
      return;
   }
   for ($i=0; $i<$arrLen; $i++) {

      $perArr[$pos] = $arr[$i]; //put i'th char in current position
      //The recursive call that move to next position with $pos+1
      findPermutations($arr, $arrLen, $size, $perArr, $pos+1, $found); 
   }
   return $found;
}

$permutations = array();
$letters = array('1','2','3');
$max_length = 6;

$permutations = findPermutations($letters, count($letters), $max_length);

for($i = 0; $i < count($permutations); $i++) {
    print ($permutations[$i].'<br/>');
}

Here is what I'm doing. I'm passing in an empty array called $permutations by reference, and as I find new permutations, I'm appending them to it. When the function findPermutations() is complete, I end up with an array of all permutation, that I can iterate over or insert. To get the formatting I'm using vsprintf, that lets me pass an array of data and apply a format (in this case %s%s|%s%s|%s%s). Lastly I'm using default argument values to make calling this function cleaner.