Trying to "move" elements in an array

here's have:
$req=@("a","b","c","d")
$current=@("c","a","d","b")

i'm trying accomplish:
$req order elements *must* in.  $current order elements in.

need take $current, , figure out "moves" need make come $req.

so, above:
1. $current[0] needs moved down 3 spots.
2. $current[1] needs moved 1 spot.
3. $current[2] needs moved down 1 spot.
4. $current[3] needs moved 2 spots.

based on #1-4 above, gives me number of spots need move element around, , "direction" match $req.

i've tried below, able take $current , create $new in proper order.

--------------------------
$req=@("a","b","c","d")
$current=@("c","a","d","b")
$new=@()

while($new.length -lt 4){
   $i=0
       foreach($item in $current){
               $looking=$new.length
               if($item -eq $req[$looking]){
                       $new+=$item
                       $diff=$i-$looking
                       "move $item $diff"
                       break
               }
               $i++
       }
}
--------------------------

result:
move 1
move b 2
move c -2
move d -1

thought home free, ran "jaykul", , pointed won't work.

problem once move "a" 1, array changes, , moves b, c , d no longer valid.

simple example of i'm trying accomplish private script.  in end, need determine specific number of moves need place right, including whether i'm moving left (+) or right (-).

here take on it:

$req=@("a","b","c","d")
[collections.arraylist]$current=@("c","a","d","b")
$sortorder = @{}
$i=0
$req | %{ $sortorder[$_] = $i++}
1..($req.count-1) | %{
    $currentelement = $current[$_];
    $currentorder = $sortorder[$currentelement]
    $newposition=-1
    $i=0
    while(($newposition -lt 0) -and ($i -lt $_)) {
        if ($currentorder -le $sortorder[$current[$i]]) { $newposition = $i }
        $i++
    }
    if ($newposition -ge 0) {
        "move $currentelement $($newposition-$_)" | write-host
        $current.removeat($_)
        $current.insert($newposition,$currentelement)
    }    
}

 

a few things note

- elements travel right left, hence, direction "-"

- insertion sort used in implementation. not efficient

- quicksort better, , hence, question, can swaps?

- choose insertion sort because resembled original description/attempt most

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