ds3.2.htm

这是清华大学所用的数据结构的电子版教材

        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>3<font face="??ì?,SimSun" lang="ZH-CN">,</font>2<font face="??ì?,SimSun" lang="ZH-CN">,</font>8<font face="??ì?,SimSun" lang="ZH-CN">,</font>1</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(*^(-*</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>*<font FACE="??ì?,SimSun" LANG="ZH-CN">入栈</font>s2</b></font><!--mstheme--></font></td>
    </tr>
    <tr>
      <td WIDTH="65" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>3</b></font><!--mstheme--></font></td>
      <td WIDTH="101" VALIGN="top" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>3<font face="??ì?,SimSun" lang="ZH-CN">,</font>2<font face="??ì?,SimSun" lang="ZH-CN">,</font>8<font face="??ì?,SimSun" lang="ZH-CN">,</font>1<font face="??ì?,SimSun" lang="ZH-CN">,</font>3</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(*^(-*</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>3<font FACE="??ì?,SimSun" LANG="ZH-CN">入栈</font>s1</b></font><!--mstheme--></font></td>
    </tr>
    <tr>
      <td WIDTH="65" VALIGN="TOP" ROWSPAN="3" height="156" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>)</b></font><!--mstheme--></font></td>
      <td WIDTH="101" VALIGN="top" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>3<font face="??ì?,SimSun" lang="ZH-CN">,</font>2<font face="??ì?,SimSun" lang="ZH-CN">,</font>8<font face="??ì?,SimSun" lang="ZH-CN">,</font>3</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(*^(-</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font size="4"><b><font color="#FFFFFF" FACE="??ì?,SimSun" LANG="ZH-CN">做</font><font color="#FFFFFF">1*3<font FACE="??ì?,SimSun" LANG="ZH-CN">，结果</font>3<font FACE="??ì?,SimSun" LANG="ZH-CN">入栈</font>s1</font></b></font><!--mstheme--></font></td>
    </tr>
    <tr>
      <td WIDTH="101" VALIGN="top" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>3<font face="??ì?,SimSun" lang="ZH-CN">,</font>2<font face="??ì?,SimSun" lang="ZH-CN">,</font>5</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(*^(</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font size="4"><b><font color="#FFFFFF" FACE="??ì?,SimSun" LANG="ZH-CN">做</font><font color="#FFFFFF">8-3<font FACE="??ì?,SimSun" LANG="ZH-CN">，结果</font>5<font FACE="??ì?,SimSun" LANG="ZH-CN">入栈</font>s2</font></b></font><!--mstheme--></font></td>
    </tr>
    <tr>
      <td WIDTH="101" VALIGN="top" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>3<font face="??ì?,SimSun" lang="ZH-CN">,</font>2<font face="??ì?,SimSun" lang="ZH-CN">,</font>5</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(*^</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font size="4"><b><font color="#FFFFFF">( </font><font FACE="??ì?,SimSun" LANG="ZH-CN" color="#FFFFFF">出栈</font></b></font><!--mstheme--></font></td>
    </tr>
    <tr>
      <td WIDTH="65" VALIGN="TOP" ROWSPAN="3" height="156" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>-</b></font><!--mstheme--></font></td>
      <td WIDTH="101" VALIGN="top" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>3<font face="??ì?,SimSun" lang="ZH-CN">,</font>32</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(*</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font size="4"><b><font color="#FFFFFF" FACE="??ì?,SimSun" LANG="ZH-CN">做</font><font color="#FFFFFF">2^5<font FACE="??ì?,SimSun" LANG="ZH-CN">，结果</font>32<font FACE="??ì?,SimSun" LANG="ZH-CN">入栈</font>s1</font></b></font><!--mstheme--></font></td>
    </tr>
    <tr>
      <td WIDTH="101" VALIGN="top" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>96</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font size="4"><b><font color="#FFFFFF" FACE="??ì?,SimSun" LANG="ZH-CN">做</font><font color="#FFFFFF">3*32<font FACE="??ì?,SimSun" LANG="ZH-CN">，结果</font>96<font FACE="??ì?,SimSun" LANG="ZH-CN">入栈</font>s1</font></b></font><!--mstheme--></font></td>
    </tr>
    <tr>
      <td WIDTH="101" VALIGN="top" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>96</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(-</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>-<font FACE="??ì?,SimSun" LANG="ZH-CN">入栈</font>s2</b></font><!--mstheme--></font></td>
    </tr>
    <tr>
      <td WIDTH="65" VALIGN="TOP" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>5</b></font><!--mstheme--></font></td>
      <td WIDTH="101" VALIGN="top" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>96<font FACE="??ì?,SimSun" LANG="ZH-CN">，</font>5</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(-</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="24" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>5<font FACE="??ì?,SimSun" LANG="ZH-CN">入栈</font>s1</b></font><!--mstheme--></font></td>
    </tr>
    <tr>
      <td WIDTH="65" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" FACE="??ì?,SimSun" LANG="ZH-CN" size="4"><b>结束符</b></font><!--mstheme--></font></td>
      <td WIDTH="101" VALIGN="top" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>91</b></font><!--mstheme--></font></td>
      <td WIDTH="84" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font color="#FFFFFF" size="4"><b>(</b></font><!--mstheme--></font></td>
      <td WIDTH="236" VALIGN="TOP" height="48" align="center"><!--mstheme--><font face="宋体">
        <p ALIGN="JUSTIFY"><font size="4"><b><font color="#FFFFFF" FACE="??ì?,SimSun" LANG="ZH-CN">做</font><font color="#FFFFFF">96-5, 
        <font FACE="??ì?,SimSun" LANG="ZH-CN">结果</font>91<font FACE="??ì?,SimSun" LANG="ZH-CN">入栈</font>s1</font></b></font><!--mstheme--></font></td>
    </tr>
  </table>
  <!--mstheme--><font face="宋体">
  </div>
</ol>
<p><font size="5" color="#FFFFFF"><b><font FACE="??ì?,SimSun" LANG="ZH-CN">图</font> 
3.7 <font FACE="??ì?,SimSun" LANG="ZH-CN">中缀表达式</font>3*2^<font FACE="??ì?,SimSun" LANG="ZH-CN">（</font>4+2*2-<font FACE="??ì?,SimSun" LANG="ZH-CN">１</font>*3<font FACE="??ì?,SimSun" LANG="ZH-CN">）</font>-5 
<font FACE="??ì?,SimSun" LANG="ZH-CN">的求值过程</font></b></font></p>
<font FACE="??ì?,SimSun" LANG="ZH-CN" SIZE="3">
<p ALIGN="JUSTIFY">&nbsp; </font><font color="#FFFFFF" size="5"><b><font FACE="??ì?,SimSun" LANG="ZH-CN">为了处理方便，编译程序常把中缀表达式首先转换成等价的后缀表达式，后缀表达式的运算符在运算对象之后。在后缀表达式中，不在引入括号，所有的计算按运算符出现的顺序，严格从左向右进行，而不用再考虑运算规则和级别。中缀表达式“</font>3*2^<font FACE="??ì?,SimSun" LANG="ZH-CN">（</font>4+2*2-1*3<font FACE="??ì?,SimSun" LANG="ZH-CN">）</font>-5 
<font FACE="??ì?,SimSun" LANG="ZH-CN">”的后缀表达式为：“</font>32422*+13*-^*5-<font FACE="??ì?,SimSun" LANG="ZH-CN">”。</font></b></font></p>
<b><font face="??ì?,SimSun" lang="ZH-CN" size="5" color="#FFFFFF">2.后缀表达式求值</font></b><font FACE="??ì?,SimSun" LANG="ZH-CN" SIZE="3">
<p ALIGN="JUSTIFY">&nbsp;&nbsp;&nbsp; </font><font face="??ì?,SimSun" lang="ZH-CN" size="5" color="#FFFFFF"><b>计算一个后缀表达式，算法上比计算一个中缀表达式简单的多。这是因为表达式中即无括号又无优先级的约束。具体做法：只使用一个对象栈，当从左向右扫描表达式时，每遇到一个操作数就送入栈中保存，每遇到一个运算符就从栈中取出两个操作数进行当前的计算，然后把结果再入栈，直到整个表达式结束，这时送入栈顶的值就是结果。</b></font></p>
<font FACE="??ì?,SimSun" LANG="ZH-CN" SIZE="3">
<p ALIGN="JUSTIFY">&nbsp;&nbsp;&nbsp; </font><font size="5" color="#FFFFFF"><b><font FACE="??ì?,SimSun" LANG="ZH-CN">下面是后缀表达式求值的算法，在下面的算法中假设，每个表达式是合乎语法的，并且假设后缀表达式已被存入一个足够大的字符数组</font>A<font FACE="??ì?,SimSun" LANG="ZH-CN">中，且以‘</font>#<font FACE="??ì?,SimSun" LANG="ZH-CN">’为结束字符，为了简化问题，限定运算数的位数仅为一位且忽略了数字字符串与相对应的数据之间的转换的问题。</font></b></font></p>
<p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><b><font size="5" color="#FFFFFF">typedef 
char datetype ;</font></b></p>
<p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><b><font size="5" color="#FFFFFF">double 
calcul_exp(char *A)</font></b></p>
<p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><font size="5" color="#FFFFFF"><b>{ 
/*<font FACE="??ì?,SimSun" LANG="ZH-CN">本函数返回由后缀表达式</font>A<font FACE="??ì?,SimSun" LANG="ZH-CN">表示的表达式运算结果</font>*/</b></font></p>
<p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><b><font size="5" color="#FFFFFF">&nbsp;Seq_Starck 
s ;</font></b></p>
<p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><b><font size="5" color="#FFFFFF">&nbsp;ch=*A++ 
; Init_SeqStack(s) ;</font></b></p>
<p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><b><font size="5" color="#FFFFFF">&nbsp;while 
( ch != ’#’ )</font></b></p>
<p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><b><font size="5" color="#FFFFFF">&nbsp;{</font></b></p>
<ol>
  <p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><font size="5" color="#FFFFFF"><b>if 
  (ch!=<font FACE="??ì?,SimSun" LANG="ZH-CN">运算符</font>) Push_SeqStack (s 
  , ch) ;</b></font></p>
  <p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><b><font size="5" color="#FFFFFF">else 
  { Pop_SeqStack (s , &amp;a) ;</font></b></p>
  <p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><font size="5" color="#FFFFFF"><b>Pop_SeqStack 
  (s , &amp;b) ; /*<font FACE="??ì?,SimSun" LANG="ZH-CN">取出两个运算量</font>*/</b></font></p>
  <p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><b><font size="5" color="#FFFFFF">switch 
  (ch).</font></b></p>
  <p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><font size="5" color="#FFFFFF"><b>{ 
  </b></font></p>
  <p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><font size="5" color="#FFFFFF"><b>&nbsp;case 
  ch= =’+’<font FACE="??ì?,SimSun" LANG="ZH-CN">：</font> c =a+b ; break ;</b></font></p>
  <p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><font size="5" color="#FFFFFF"><b>&nbsp;case 
  ch= =’-’<font FACE="??ì?,SimSun" LANG="ZH-CN">：</font> c=a-b ; break ;</b></font></p>
  <p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><font size="5" color="#FFFFFF"><b>&nbsp;case 
  ch= =’*’<font FACE="??ì?,SimSun" LANG="ZH-CN">：</font> c=a*b ; break ;</b></font></p>
  <p ALIGN="justify" style="margin-top: 0; margin-bottom: 0"><font size="5" color="#FFFFFF"><b>&nbsp;case