1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>prev_permutation</title> 5<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../../index.html" title="Chapter 1. Range 2.0"> 8<link rel="up" href="../permutation.html" title="Permutation algorithms"> 9<link rel="prev" href="next_permutation.html" title="next_permutation"> 10<link rel="next" href="../new.html" title="New algorithms"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="next_permutation.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../permutation.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../new.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h5 class="title"> 27<a name="range.reference.algorithms.permutation.prev_permutation"></a><a class="link" href="prev_permutation.html" title="prev_permutation">prev_permutation</a> 28</h5></div></div></div> 29<h6> 30<a name="range.reference.algorithms.permutation.prev_permutation.h0"></a> 31 <span class="phrase"><a name="range.reference.algorithms.permutation.prev_permutation.prototype"></a></span><a class="link" href="prev_permutation.html#range.reference.algorithms.permutation.prev_permutation.prototype">Prototype</a> 32 </h6> 33<p> 34</p> 35<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">BidirectionalRange</span><span class="special">></span> 36<span class="keyword">bool</span> <span class="identifier">prev_permutation</span><span class="special">(</span><span class="identifier">BidirectionalRange</span><span class="special">&</span> <span class="identifier">rng</span><span class="special">);</span> 37 38<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">BidirectionalRange</span><span class="special">></span> 39<span class="keyword">bool</span> <span class="identifier">prev_permutation</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">BidirectionalRange</span><span class="special">&</span> <span class="identifier">rng</span><span class="special">);</span> 40 41<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">BidirectionalRange</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Compare</span><span class="special">></span> 42<span class="keyword">bool</span> <span class="identifier">prev_permutation</span><span class="special">(</span><span class="identifier">BidirectionalRange</span><span class="special">&</span> <span class="identifier">rng</span><span class="special">,</span> <span class="identifier">Compare</span> <span class="identifier">pred</span><span class="special">);</span> 43 44<span class="keyword">template</span><span class="special"><</span><span class="keyword">class</span> <span class="identifier">BidirectionalRange</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Compare</span><span class="special">></span> 45<span class="keyword">bool</span> <span class="identifier">prev_permutation</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">BidirectionalRange</span><span class="special">&</span> <span class="identifier">rng</span><span class="special">,</span> <span class="identifier">Compare</span> <span class="identifier">pred</span><span class="special">);</span> 46</pre> 47<p> 48 </p> 49<h6> 50<a name="range.reference.algorithms.permutation.prev_permutation.h1"></a> 51 <span class="phrase"><a name="range.reference.algorithms.permutation.prev_permutation.description"></a></span><a class="link" href="prev_permutation.html#range.reference.algorithms.permutation.prev_permutation.description">Description</a> 52 </h6> 53<p> 54 <code class="computeroutput"><span class="identifier">prev_permutation</span></code> transforms 55 the range of elements <code class="computeroutput"><span class="identifier">rng</span></code> 56 into the lexicographically next smaller permutation of the elements if 57 such a permutation exists. If one does not exist then the range is transformed 58 into the lexicographically largest permutation and <code class="computeroutput"><span class="keyword">false</span></code> 59 is returned. <code class="computeroutput"><span class="keyword">true</span></code> is returned 60 when the next smaller permutation is successfully generated. 61 </p> 62<p> 63 The ordering relationship is determined by using <code class="computeroutput"><span class="keyword">operator</span><span class="special"><</span></code> in the non-predicate versions, and 64 by evaluating <code class="computeroutput"><span class="identifier">pred</span></code> in 65 the predicate versions. 66 </p> 67<h6> 68<a name="range.reference.algorithms.permutation.prev_permutation.h2"></a> 69 <span class="phrase"><a name="range.reference.algorithms.permutation.prev_permutation.definition"></a></span><a class="link" href="prev_permutation.html#range.reference.algorithms.permutation.prev_permutation.definition">Definition</a> 70 </h6> 71<p> 72 Defined in the header file <code class="computeroutput"><span class="identifier">boost</span><span class="special">/</span><span class="identifier">range</span><span class="special">/</span><span class="identifier">algorithm</span><span class="special">/</span><span class="identifier">permutation</span><span class="special">.</span><span class="identifier">hpp</span></code> 73 </p> 74<h6> 75<a name="range.reference.algorithms.permutation.prev_permutation.h3"></a> 76 <span class="phrase"><a name="range.reference.algorithms.permutation.prev_permutation.requirements"></a></span><a class="link" href="prev_permutation.html#range.reference.algorithms.permutation.prev_permutation.requirements">Requirements</a> 77 </h6> 78<p> 79 <span class="bold"><strong>For the non-predicate versions:</strong></span> 80 </p> 81<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 82<li class="listitem"> 83 <code class="computeroutput"><span class="identifier">BidirectionalRange</span></code> 84 is a model of the <a class="link" href="../../../concepts/bidirectional_range.html" title="Bidirectional Range">Bidirectional 85 Range</a> Concept. 86 </li> 87<li class="listitem"> 88 <code class="computeroutput"><span class="identifier">BidirectionalRange</span></code> 89 is mutable. 90 </li> 91<li class="listitem"> 92 <code class="computeroutput"><span class="identifier">BidirectionalRange</span></code>'s 93 value type is a model of the <code class="computeroutput"><span class="identifier">LessThanComparableConcept</span></code>. 94 </li> 95<li class="listitem"> 96 The ordering of objects of type <code class="computeroutput"><span class="identifier">BidirectionalRange</span></code>'s 97 value type is a <span class="bold"><strong><span class="emphasis"><em>strict weak ordering</em></span></strong></span>, 98 as defined in the <code class="computeroutput"><span class="identifier">LessThanComparableConcept</span></code> 99 requirements. 100 </li> 101</ul></div> 102<p> 103 <span class="bold"><strong>For the predicate versions:</strong></span> 104 </p> 105<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "> 106<li class="listitem"> 107 <code class="computeroutput"><span class="identifier">BidirectionalRange</span></code> 108 is a model of the <a class="link" href="../../../concepts/bidirectional_range.html" title="Bidirectional Range">Bidirectional 109 Range</a> Concept. 110 </li> 111<li class="listitem"> 112 <code class="computeroutput"><span class="identifier">BidirectionalRange</span></code> 113 is mutable. 114 </li> 115<li class="listitem"> 116 <code class="computeroutput"><span class="identifier">Compare</span></code> is a model 117 of the <code class="computeroutput"><span class="identifier">StrictWeakOrderingConcept</span></code>. 118 </li> 119<li class="listitem"> 120 <code class="computeroutput"><span class="identifier">BidirectionalRange</span></code>'s 121 value type is convertible to both of <code class="computeroutput"><span class="identifier">Compare</span></code>'s 122 argument types. 123 </li> 124</ul></div> 125<h6> 126<a name="range.reference.algorithms.permutation.prev_permutation.h4"></a> 127 <span class="phrase"><a name="range.reference.algorithms.permutation.prev_permutation.complexity"></a></span><a class="link" href="prev_permutation.html#range.reference.algorithms.permutation.prev_permutation.complexity">Complexity</a> 128 </h6> 129<p> 130 Linear. At most <code class="computeroutput"><span class="identifier">distance</span><span class="special">(</span><span class="identifier">rng</span><span class="special">)</span> <span class="special">/</span> <span class="number">2</span></code> 131 swaps. 132 </p> 133</div> 134<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 135<td align="left"></td> 136<td align="right"><div class="copyright-footer">Copyright © 2003-2010 Thorsten Ottosen, 137 Neil Groves<p> 138 Distributed under the Boost Software License, Version 1.0. (See accompanying 139 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 140 </p> 141</div></td> 142</tr></table> 143<hr> 144<div class="spirit-nav"> 145<a accesskey="p" href="next_permutation.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../permutation.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../new.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 146</div> 147</body> 148</html> 149
