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RE: [xsl] Show all permutations of N coins ... without using recursion?

Subject: RE: [xsl] Show all permutations of N coins ... without using recursion?
From: "Costello, Roger L." <costello@xxxxxxxxx>
Date: Sat, 31 Aug 2013 16:18:07 +0000

Jacob Mal} wrote:

>  You just iterate from 1 to 2^N, each step gives
> you one output sequence, you just have to convert
> it to the desired format.

Thank you very much!

I did as you suggested and it works great.

The below stylesheet shows the permutations of N coins, implemented in two
ways: (1) using recursion, and (2) using iteration.

By the way, I recently learned about the xsl:iterate instruction. Wow! Such a
useful instruction. How have I lived without it all these years.

           Show all permutations of N coins
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"

    <xsl:output method="text"/>

    <xsl:template match="/">
        <xsl:value-of select="f:show-coins-using-recursion(3, '')" />
        <xsl:value-of select="f:show-coins-using-iteration(3)" />

    <xsl:function name="f:show-coins-using-iteration">
        <xsl:param name="N" as="xs:integer" />

        <xsl:for-each select="(0 to xs:integer(math:pow(2, $N) - 1))">
            <xsl:variable name="number" select="." />
            <xsl:iterate select="1 to $N">
                <xsl:param name="num" select="$number" />
                <xsl:param name="coins" select="''" />

                <xsl:variable name="coin" select="if (($num mod 2) eq 0) then
'H' else 'T'" />
                    <xsl:with-param name="num" select="$num idiv 2" />
                    <xsl:with-param name="coins" select="concat($coins,
$coin)" />
                    <xsl:value-of select="concat($coins, ' ')" />

    <xsl:function name="f:show-coins-using-recursion">
        <xsl:param name="N" as="xs:integer" />
        <xsl:param name="coins" as="xs:string*" />

            <xsl:when test="$N eq 0">
                <xsl:value-of select="concat($coins, ' ')" />
                <xsl:for-each select="('H','T')">
                    <xsl:value-of select="f:show-coins-using-recursion($N - 1,
concat($coins, .))" />


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