This question has been asked in many forms. I want to take an array in PHP and get all possible combinations / permutations. I want both permutations of the whole set as well as a partial set.
My twist on this question is asking how can I remove sequential duplicates from within the result items. I got close to what I wanted by using " PHP take all combinations " and adding a function:
$words = array('a','b','c');
function permutations($arr,$n)
{
$res = array();
foreach ($arr as $w)
{
if ($n==1) $res[] = $w;
else
{
$perms = permutations($arr,$n-1);
foreach ($perms as $p)
{
$res[] = $w." ".$p;
}
}
}
return $res;
}
function get_all_permutations($words=array())
{
$r = array();
for($i=sizeof($words);$i>0;$i--)
{
$r = array_merge(permutations($words,$i),$r);
}
return $r;
}
$permutations = get_all_permutations($words);
print_r($permutations);
That will output:
Array
(
[0] => a
[1] => b
[2] => c
[3] => a a
[4] => a b
[5] => a c
[6] => b a
[7] => b b
[8] => b c
[9] => c a
[10] => c b
[11] => c c
[12] => a a a
[13] => a a b
[14] => a a c
[15] => a b a
[16] => a b b
[17] => a b c
[18] => a c a
[19] => a c b
[20] => a c c
[21] => b a a
[22] => b a b
[23] => b a c
[24] => b b a
[25] => b b b
[26] => b b c
[27] => b c a
[28] => b c b
[29] => b c c
[30] => c a a
[31] => c a b
[32] => c a c
[33] => c b a
[34] => c b b
[35] => c b c
[36] => c c a
[37] => c c b
[38] => c c c
)
I know I could look through the output once the set has been generated, but is it possible to remove the sequential duplicates during generation?
Examples which should be transformed / removed:
c c cwould be the same ascc c bwould be the same asc bc c c c cwould also be the same asc(if the set was larger)
Notes:
- I'm not great with recursion but there is probably a fancy way to combine the two functions I have into one.
- Right now the output sets are strings but I don't mind if they are arrays instead (if that makes things easier)
