Feature #7: Detecting a Protein
Explore how to determine if a nucleotide sequence is a protein by checking for palindromic permutations. Learn to implement an efficient hashmap solution that counts nucleotide occurrences and evaluates palindrome feasibility. Understand time and space complexities relevant to this computational biology problem.
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Description
Proteins are characterized by long palindrome sequences of nucleotides, where a character represents each nucleotide. We have received a sample that may be a protein. However, the nucleotides in this sample may have been rearranged due to a mutation.
Given a sequence of nucleotides, our task is to check if any true if it is a protein, and return false if it is not a protein.
The following examples may help to clarify this problem:
Solution
If some permutation of a sequence with an even length is a palindrome, every nucleotide in the sequence must appear an even number of times. Similarly, if a permutation of a sequence with an odd length is a palindrome, every nucleotide, except one, must appear an even number of times. So, in the case of a sequence being a palindrome and when there is a sequence of an odd length, the number of nucleotides with an odd number of occurrences cannot exceed 1. Similarly, in the case of a sequence with an even length, the number of nucleotides with an odd number of occurrences is 0.
Suppose we are given a sequence, s, and we expect all the nucleotides in s to appear an even number of times, except for perhaps one of them. So we can check if a nucleotide appears an odd number of times in the sequence. If more than one nucleotides appear an odd number of times, then s cannot be a palindrome. To do so, we can use a hashmap that stores the ...