应用该多层概要数据结构，实现了面向数据流的多层频繁项集的动态近似查找算法。
Applying the hierarchical sketch, an algorithm that finds hierarchical frequent items over data streams dynamically and approximately was implemented.
由于随机哈希函数不可逆，目前的概要数据结构不得不遍历关键字地址空间以查找和估计频繁项集。
Due to the irreversibility of random hash mapping, current sketch data structures have to traverse the key address space to find frequent items.
概要设计：本程序所使用的数据结构是树和线性表，所使用的算法主要有堆排序、赫夫曼算法。
Summary of design: the procedures used by the data structure is linear tree and table, the algorithm used by the main sculpture, in order Huffman algorithm.
概要设计：本程序所使用的数据结构是树和线性表，所使用的算法主要有堆排序、赫夫曼算法。
Summary of design: the procedures used by the data structure is linear tree and table, the algorithm used by the main sculpture, in order Huffman algorithm.
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