PHP drop box, that is: multiple arrays are arbitrarily arranged into a large array, and must contain all the original array

PHP array arbitrary permutation combination

And the department discussed it all morning, without discussing the results, the basic requirements are as follows:
Assume:
$a = Array (' a ');
$b = Array (' B ');
$c = Array (' C ');
$d = Array (' d ');

Get the following result from a function:
Array
A+b+c+d,
Ab+c+d,
Ac+b+d,
Ad+b+c,
Bc+ad,
Bc+a+d,
Bd+ac,
Bd+a+c
Cd+ab,
Cd+a+b,
Abc+a,
Acd+b,
Abd+c,
Bcd+a,
...
)

That is, to get the combination of all arrays, any combination of array ordering is not necessarily in order, but requires that the combination must appear all elements.
Is there an expert to give a good algorithm or idea?

Reply to discussion (solution)

Implemented with ready-made functions, not optimized

 $a = Array (' A ', ' B ', ' C ', ' d '); $res = Array (); foreach (arrangement ($a) as $v) {$res = arr Ay_merge ($res, foo (Explode (", trim ($v))));} Print_r ($res);//Arrange arrangementfunction arrangement ($arr = Array (), $res = ") {if (! Is_array ($arr)) $arr = Str_split ($a  RR);  if (empty ($arr)) $array [] = $res;    else foreach ($arr as $k = + $v) {unset ($arr [$k]); foreach (Arrangement ($arr, $res.    "$v") as $t) $array [] = $t;  $arr [$k] = $v; } return $array;}  function foo ($ar) {$res = array ();    if (count ($ar) > 2) {$t = Array_shift ($ar);       foreach (foo ($ar) as $v) {$res [] = "$t $v";    $res [] = "$t + $v";     }}else {$res [] = "$ar [0] $ar [1]";  $res [] = "$ar [0]+ $ar [1]"; } return $res;} 

Array ([0] = ABCD [1] = A+BCD [2] = AB+CD [3] = A+B+CD [4] = = Abc+d [5] = = A+bc+d    [6] = ab+c+d [7] = a+b+c+d [8] = ABDC [9] = A+BDC [Ten] = AB+DC [one] = A+B+DC    [[] = abd+c [] = a+bd+c [+] = ab+d+c [] = a+b+d+c [+] = acdb [+] = a+cdb     [+] = ac+db [] = a+c+db [+] = acd+b [+] = a+cd+b [] = ac+d+b [] = A+c+d+b    [[] = ACBD [] = A+CBD [] = AC+BD [+] = A+C+BD [+] = acb+d [+] = A+cb+d     [+] = ac+b+d [+] = a+c+b+d [+] = ADBC [+] = A+DBC [+] = AD+BC [+] = A+D+BC [[+] = adb+c [PNS] = a+db+c [] = ad+b+c [] = a+d+b+c [+] = ADCB [+] = A+DC b [[+] = AD+CB [] = A+D+CB [] + adc+b [[] = A+dc+b [] [] = ad+c+b [+] = A+d +c+b [[] = BCDA   [+] = B+CDA [[[]] = Bc+da [Wuyi] + b+c+da [] = bcd+a [+] = b+cd+a [si] = bc+d+a     [[+] = b+c+d+a [[+]] = BCAD [[+]] = B+cad [+] = Bc+ad [+] = B+c+ad [+] = Bca+d [B+ca+d] = = [+] = bc+a+d [+] = b+c+a+d [+] = BDAC [+] = B+DAC [$] = Bd+a c [[+] = B+d+ac [] = bda+c [] = b+da+c [] = Bd+a+c [[] = [] = B+d+a+c [] + b DCA [B+DCA] = [all] = BD+CA [[]] = B+D+CA [[] [] = bdc+a [All] = b+dc+a [+] = BD +c+a [[+] = b+d+c+a [] = BACD [Bayi] = B+ACD [[+] = BA+CD [the] [] = B+A+CD [+] = b Ac+d [[] = b+ac+d [[+] = ba+c+d [] [[]] = b+a+c+d [A] = [[]] [] = BADC [[]] = = BA+DC [[] = [] = B+A+DC [[]] = bad+c [] = b+ad+c [94] = Ba+d+c [up] = B+a+d+c [] =&G T Cdab [+] = c+DAB [98] = Cd+ab [in] = C+d+ab [+] = cda+b [101] = c+da+b [102] = cd+a+b [103] =&G T c+d+a+b [104] = CDBA [[+] = C+DBA [106] = CD+BA [107] = C+D+BA [108] = Cdb+a [109]    = C+db+a [[+] = cd+b+a [111] = C+d+b+a [in] + cabd [113] = c+abd [all] = CA+BD  [C+A+BD] = [$] = cab+d [117] = c+ab+d [118] = ca+b+d [119] = c+a+b+d [+] = CADB [121] = c+adb [122] = CA+DB [123] = c+a+db [124] = Cad+b [[]] = c+ad+b [126]    = ca+d+b [127] = c+a+d+b [+] = CBDA [129] = C+BDA [[] [] = Cb+da [131] = C+b+da [PPI] = cbd+a [133] = C+bd+a [134] = Cb+d+a [135] = c+b+d+a [136] = Cbad [137] + C +bad [138] = Cb+ad [139] = C+b+ad [[+] = cba+d [141] = c+ba+d [142] = cb+a+d [143] = C+b+a+d [144] = DABC [145] = D+ABC [146] = DA+BC [147] = D+A+BC [148] = dab+c [149] + d+ab+c [Da+b+c] = [151] = d+a+b+c [] = DACB [153] = D+ACB [154] = DA+CB [155] = d+ A+CB [156] = dac+b [157] = d+ac+b [158] = da+c+b [159] = D+a+c+b [[]] = DBCA [161]    = D+BCA [162] = DB+CA [163] = D+B+CA [164] = dbc+a [165] = D+bc+a [166] = Db+c+a [167] = d+b+c+a [168] = DBAC [169] = D+BAC [[+] = db+ac [171] = D+B+AC [172] = db a+c [173] = d+ba+c [174] = db+a+c [175] = d+b+a+c [176] = Dcab [177] = = D+cab [178] =    > dc+ab [179] = D+c+ab [[+] = dca+b [181] = d+ca+b [182] = dc+a+b [183] = D+c+a+b [184] = DCBA [185] = D+CBA [186] = Dc+ba [187] = D+C+BA [188] = dcb+a [189] = D+c B+a [] = dc+b+A [191] = d+c+b+a) 

Thank you moderator, function I have words, go to heavy OK.
Go to the heavy after again post, more Mr. Chia, later confirmed.

Is there a repetition? Apparently not.
Print_r (Array_unique ($res));
And
Print_r ($res);
The same result!

Var_dump (count ($res) = = Count (Array_unique ($res)));
BOOL (TRUE)

Sorry moderator, I did not explain clearly, a+b+c+d and B+a+c+d, D+c+a+b and so on.

