RosettaCodeData/Task/Permutations-by-swapping/PowerShell/permutations-by-swapping.psh

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function output([Object[]]$A, [Int]$k, [ref]$sign)
{
"Perm: [$([String]::Join(', ', $A))] Sign: $($sign.Value)"
}
function permutation([Object[]]$array)
{
function generate([Object[]]$A, [Int]$k, [ref]$sign)
{
if($k -eq 1)
{
output $A $k $sign
$sign.Value = -$sign.Value
}
else
{
$k -= 1
generate $A $k $sign
for([Int]$i = 0; $i -lt $k; $i += 1)
{
if($i % 2 -eq 0)
{
$A[$i], $A[$k] = $A[$k], $A[$i]
}
else
{
$A[0], $A[$k] = $A[$k], $A[0]
}
generate $A $k $sign
}
}
}
generate $array $array.Count ([ref]1)
}
permutation @(0, 1, 2)
""
permutation @(0, 1, 2, 3)