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2000题经典数据结构试题

<p class=MsoNormal style='margin-left:.3pt;text-indent:-.3pt;tab-stops:list 0cm'><span
style='font-family:宋体'>（<span lang=EN-US>2</span>）索引非顺序文件适合随机存取，不适合顺序存取，因主关键字未排序，若顺序存取会引起磁头频繁移动。索引顺序文件是最常用的文件组织，因主文件有序，既可顺序存取也可随机存取。索引非顺序文件是稠密索引，可以“预查找”，索引顺序文件是稀疏索引，不能“预查找”，但由于索引占空间较少，管理要求低，提高了索引的查找速度。<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal style='margin-left:.3pt;text-indent:-.3pt;tab-stops:list 0cm'><span
style='font-family:宋体'>（<span lang=EN-US>3</span>）散列文件也称直接存取文件，根据关键字的散列函数值和处理冲突的方法，将记录散列到外存上。这种文件组织只适用于像磁盘那样的直接存取设备，其优点是文件随机存放，记录不必排序，插入、删除方便，存取速度快，无需索引区，节省存储空间。缺点是散列文件不能顺序存取，且只限于简单查询。经多次插入、删除后，文件结构不合理，需重组文件，这很费时。<span
lang=EN-US><o:p></o:p></span></span></p>

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lang=EN-US style='font-family:宋体'>14</span><span style='font-family:宋体'>．类似最优二叉树（哈夫曼树），可先合并含较少记录的文件，后合并较多记录的文件，使移动次数减少。见下面的哈夫曼树。<span
lang=EN-US><o:p></o:p></span></span></p>

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