Ressource pédagogique : 2.7. The algorithm design trade-off

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We saw how to increase the efficiencyof our algorithm through the introduction of a data structure. Now let's see if we can do even better. We had a table of index and weexplain how the use of these small arrays allowed us to increase the efficiency that is to reduce the number of comparison to be executed when looking up a triplet in the genetic code. Now what I propose is an alternative to this data structure, it's to compute the indexes. OK. So we have this algorithm which uses here a function. You are now familiar with thisnotion of function, the idea is to fragment the complexity ofan algorithm by isolating parts of it into a function. Here the function,we will start with the function. It's quite simple, as an input ittakes a character and it returns an integer, if the character isT it returns One, if C Two and so on and so on. So it's a very simple function, it's only a case instruction OK. So for eachof the four letters of the DNA alphabet, it returnsOne, Two, Three or Four. OK. Now our famous Look up GeneticCode function is still the same as they are seen from theoutside that is three letters, three characters as input and itreturns a character which is the corresponding aminoacid in the genetic code. The genetic code again is here a simplearray of 64 rows of characters. It is supposed to be knowninside the function.

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