[
        0 => "791cb6f72ba132e6",1 => "fb5d37c52cb65b54d03758237670b8db",2 => "72e90f1d3a8ed558",3 => "04f4aedf1862add8",4 => "648585876e5a8157",],"sz002293" => [
        0 => "791cb6f72ba132e5",1 => "fb5d37c52cb65b54d03758237670b8dc",2 => "72e90f1d3a8ed559",5 => "eace7d8a9b7231be",]
];
//$uids = array_merge(... array_values($arr));echo '共'.count($uids);

$uids = array_reduce($arr,function($a,$b){

return array_merge($a,array_values($b));

},[]);

print_r($uids);

Array

(

[0] => 791cb6f72ba132e6

[1] => fb5d37c52cb65b54d03758237670b8db

[2] => 72e90f1d3a8ed558

[3] => 04f4aedf1862add8

[4] => 648585876e5a8157

[5] => 791cb6f72ba132e5

[6] => fb5d37c52cb65b54d03758237670b8dc

[7] => 72e90f1d3a8ed559

[8] => 04f4aedf1862add8

[9] => 648585876e5a8157

[10] => eace7d8a9b7231be

)

$result=[];

foreach($arr as $symbol=>$v){

foreach($v as $user){

$result[$user][]=$symbol;

}

}

print_r($result);

Array

(

[791cb6f72ba132e6] => Array

(

[0] => sz002292

)
[fb5d37c52cb65b54d03758237670b8db] => Array
    (
        [0] => sz002292
    )

[72e90f1d3a8ed558] => Array
    (
        [0] => sz002292
    )

[04f4aedf1862add8] => Array
    (
        [0] => sz002292
        [1] => sz002293
    )

[648585876e5a8157] => Array
    (
        [0] => sz002292
        [1] => sz002293
    )

[791cb6f72ba132e5] => Array
    (
        [0] => sz002293
    )

[fb5d37c52cb65b54d03758237670b8dc] => Array
    (
        [0] => sz002293
    )

[72e90f1d3a8ed559] => Array
    (
        [0] => sz002293
    )

[eace7d8a9b7231be] => Array
    (
        [0] => sz002293
    )
)

$r=[];

foreach($result as $uid => $v) {
        $key = md5(implode(',',$v));
        if (!isset($r[$key])) {
            $r[$key]['symbols'] = $v;
        }
        $r[$key]['uid'][] = $uid;
    }        

    print_r($r);
    Array
(

[ad3dc3c74bbbe0385cad8b14736b8f23] => Array

(

[symbols] => Array

(

[0] => sz002292

)
        [uid] => Array
            (
                [0] => 791cb6f72ba132e6
                [1] => fb5d37c52cb65b54d03758237670b8db
                [2] => 72e90f1d3a8ed558
            )

    )

[0dd<a href="https://www.jb51.cc/tag/301/" target="_blank" class="keywords">301</a>afdb97c9cd6d6c9521f562e271] => Array
    (
        [symbols] => Array
            (
                [0] => sz002292
                [1] => sz002293
            )

        [uid] => Array
            (
                [0] => 04f4aedf1862add8
                [1] => 648585876e5a8157
            )

    )

[c21ecf05fca513d6ceecc884db88c8b2] => Array
    (
        [symbols] => Array
            (
                [0] => sz002293
            )

        [uid] => Array
            (
                [0] => 791cb6f72ba132e5
                [1] => fb5d37c52cb65b54d03758237670b8dc
                [2] => 72e90f1d3a8ed559
                [3] => eace7d8a9b7231be
            )

    )
)