ds6.5.1.htm

这是清华大学所用的数据结构的电子版教材

<p align="center" style="margin-top: 0; margin-bottom: 0"><img border="0" src="ds6.5.3.gif" width="493" height="254"></p>
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<p align="center" style="margin-top: 0; margin-bottom: 0"><font size="4" color="#FFFFFF"><span style="mso-bidi-font-size: 10.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA"><b><span style="mso-bidi-font-size: 10.0pt; font-family: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman; mso-bidi-font-family: Times New Roman; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">图</span><span lang="EN-US" style="mso-bidi-font-size: 10.0pt; font-family: Times New Roman; mso-fareast-font-family: 宋体; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">6.17<span style="mso-spacerun: yes; mso-bidi-font-size: 10.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">&nbsp;  
</span></span><span style="mso-bidi-font-size: 10.0pt; font-family: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman; mso-bidi-font-family: Times New Roman; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">具有相同叶子结点和不同带权路径长度的二叉树</span></b></span></font></p>
<p class="MsoNormal"><b><font size="5" color="#FFFFFF"><span style="mso-spacerun: yes">&nbsp;</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:
&quot;Times New Roman&quot;">&nbsp;  
由此可见，由相同权值的一组叶子结点所构成的二叉树有不同的形态和不同的带权路径长度，那么如何找到带权路径长度最小的二叉树（即哈夫曼树）呢？根据哈夫曼树的定义，一棵二叉树要使其</span><span lang="EN-US">WPL</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;
mso-hansi-font-family:&quot;Times New Roman&quot;">值最小，必须使权值越大的叶结点越靠近根结点，而权值越小的叶结点越远离根结点。哈夫曼（</span><span lang="EN-US">Haffman</span><span style="font-family:宋体;mso-ascii-font-family:
&quot;Times New Roman&quot;;mso-hansi-font-family:&quot;Times New Roman&quot;">）依据这一特点提出了一种方法，这种方法的基本思想是：</span></font></b></p>
<p class="MsoNormal"><span style="mso-spacerun: yes" lang="EN-US"><font size="5" color="#FFFFFF"><b>&nbsp;&nbsp;&nbsp;  
</b></font></span><font size="5" color="#FFFFFF"><b><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:
&quot;Times New Roman&quot;">（</span><span lang="EN-US">1</span><span style="font-family:
宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:&quot;Times New Roman&quot;">）由给定的</span><span lang="EN-US">n</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;
mso-hansi-font-family:&quot;Times New Roman&quot;">个权值</span><span lang="EN-US">{W1</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:
&quot;Times New Roman&quot;">，</span><span lang="EN-US">W2</span><span style="font-family:
宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:&quot;Times New Roman&quot;">，</span><span lang="EN-US">…</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;
mso-hansi-font-family:&quot;Times New Roman&quot;">，</span><span lang="EN-US">Wn}</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:
&quot;Times New Roman&quot;">构造</span><span lang="EN-US">n</span><span style="font-family:
宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:&quot;Times New Roman&quot;">棵只有一个叶结点的二叉树，从而得到一个二叉树的集合</span><span lang="EN-US">F</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;
mso-hansi-font-family:&quot;Times New Roman&quot;">＝</span><span lang="EN-US">{T1</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:
&quot;Times New Roman&quot;">，</span><span lang="EN-US">T2</span><span style="font-family:
宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:&quot;Times New Roman&quot;">，</span><span lang="EN-US">…</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;
mso-hansi-font-family:&quot;Times New Roman&quot;">，</span><span lang="EN-US">Tn}</span><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:
&quot;Times New Roman&quot;">；</span></b></font></p>
<p class="MsoNormal"><span style="mso-spacerun: yes" lang="EN-US"><font size="5" color="#FFFFFF"><b>&nbsp;&nbsp;&nbsp;  
</b></font></span><font size="5" color="#FFFFFF"><b><span style="font-family:宋体;mso-ascii-font-family:&quot;Times New Roman&quot;;mso-hansi-font-family:
&quot;Times New Roman&quot;">（</span><span lang="EN-US">2</span><span style="font-family: