Get-ElementCombination.ps1
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<#PSScriptInfo
.DESCRIPTION Finds combinations of elements .VERSION 1.0.0 .GUID 4d2c4fef-77ed-453e-ab19-f0b5d411ab38 .AUTHOR Lee Holmes #> <# .SYNOPSIS Finds combinations of elements .EXAMPLE PS > Get-ElementCombination -Base 2 -MaxLength 3 | Foreach-Object { $_ -join "," } 0,0,0 0,0,1 0,1,0 0,1,1 1,0,0 1,0,1 1,1,0 1,1,1 PS > $chars = 'a','b','c' PS > Get-ElementCombination -Base 3 -MaxLength 2 | % { -join ($_ | % { $chars[$_] }) } aa ab ac ba bb bc ca cb cc #> #> param( ## The number of elements in the set. $Base, ## How long can the sequences be? $MaxLength ) ## Hold the sequence $currentValue = New-Object Int[] $MaxLength $currentLength = 1 ,$currentValue.Clone() while ($true) { $currentIndex = $maxLength - 1 while ($true) { ## Increment the final element. If we haven't overflowed the ## base, then we're done $currentValue[$currentIndex]++; if ($currentValue[$currentIndex] -lt $Base) { break; } ## If we did overflow the base, then set this element back to ## zero and start working on the element to the left. $currentValue[$currentIndex] = 0; $currentIndex--; ## If we've gone past our max length, exit. if($currentIndex -lt 0) { return } ## If we've added a new element (i.e.: gone further to the left ## than we have before), we now have a new current length. if($currentLength -lt ($maxLength - $currentIndex)) { $currentLength = $maxLength - $currentIndex } } ## Output the current combination ,$currentValue.Clone() } |