Jacob Malý 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";
xmlns:map="http://www.w3.org/2005/xpath-functions/map";
xmlns:math="http://www.w3.org/2005/xpath-functions/math";
xmlns:xs="http://www.w3.org/2001/XMLSchema";
xmlns:f="function"
version="3.0">
<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:template>
<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 (($num mod 2) eq 0) then
'H' else 'T'" />
<xsl:next-iteration>
<xsl:with-param name="num" select="$num idiv 2" />
<xsl:with-param name="coins" select="concat($coins, $coin)"
/>
</xsl:next-iteration>
<xsl:on-completion>
<xsl:value-of select="concat($coins, ' ')" />
</xsl:on-completion>
</xsl:iterate>
</xsl:for-each>
</xsl:function>
<xsl:function name="f:show-coins-using-recursion">
<xsl:param name="N" as="xs:integer" />
<xsl:param name="coins" as="xs:string*" />
<xsl:choose>
<xsl:when test="$N eq 0">
<xsl:value-of select="concat($coins, ' ')" />
</xsl:when>
<xsl:otherwise>
<xsl:for-each select="('H','T')">
<xsl:value-of select="f:show-coins-using-recursion($N - 1,
concat($coins, .))" />
</xsl:for-each>
</xsl:otherwise>
</xsl:choose>
</xsl:function>
</xsl:stylesheet>
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