[英]Permutations of subsets and subsequent run-time analysis
I have 2 questions: 我有两个问题:
I would like to generate the permutations of subsets eg There are 20 possible amino acids and 5 positions where they can occur. 我想生成子集的排列,例如,有20种可能的氨基酸和5种可能发生的位置。 What are the total permutations that can occur (in text)
可能发生的总排列是什么(文本中)
Once I have this list of permutations certain values will be assinged to each one and I would like to look up any given permutation at run time. 一旦我有了这个排列列表,就会给每个值添加一些值,我想在运行时查找任何给定的排列。 The first idea that comes to mind is a look-up table, but I was wondering if there might be a better way of doing this.
想到的第一个想法是一个查找表,但我想知道是否有更好的方法来做到这一点。
You want combinations of length 5, not permutations. 你想要长度为5的组合,而不是排列组合。 This is a standard problem, which can be solved with recursion.
这是一个标准问题,可以通过递归来解决。 Use
CombinationGenerator
if you don't want to write it yourself. 如果您不想自己编写,请使用
CombinationGenerator
。
Number the combinations using base 20 (not to be confused with the chemical definition of base). 使用基数20对组合进行编号(不要与碱的化学定义混淆)。 Use a hashtable if you'll be storing data for a limited subset of combinations, or a look-up array if you'll be most of them.
如果您要为有限的组合子集存储数据,请使用哈希表;如果您是大多数组合,则使用查找数组。
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