POJ1007算法解析

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于 2017-08-08 13:58:38 发布 · 569 阅读

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#算法

这篇博客介绍了POJ1007问题，即DNA字符串的排序算法。文章讨论了如何计算DNA序列的逆序对数量作为排序标准，并给出了一个精简的G++代码实现。博主提供了样例输入和输出，解释了在相同排序条件下如何保持原始顺序。

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POJ1007
DNA Sorting
Time Limit: 1000MS Memory Limit: 10000K
Total Submissions: 102642 Accepted: 41111

Description
One measure of unsortedness'' in a sequence is the number of pairs of entries that are out of order with respect to each other. For instance, in the letter sequenceDAABEC”, this measure is 5, since D is greater than four letters to its right and E is greater than one letter to its right. This measure is called the number of inversions in the sequence. The sequence AACEDGG'' has only one inversion (E and D)---it is nearly sorted---while the sequenceZWQM” has 6 inversions (it is as unsorted as can be—exactly the reverse of sorted).

You are responsible for cataloguing a sequence of DNA strings (sequences containing only the four letters A, C, G, and T). However, you want to catalog them, not in alphabetical order, but rather in order of sortedness'', frommost sorted” to “least sorted”. All the string