Feature #3: Locate Protein
Explore how to detect specific proteins in DNA by finding the longest palindromic sequence in a string of nucleotides. This lesson teaches you to use two-pointer techniques to locate palindromes, understand their biological significance, and implement an efficient algorithm with O(N²) time complexity and O(1) space.
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Description
Experiments have shown that a certain protein provides immunity against a specific virus. Unfortunately, the presence of the protein can’t be determined based on an exact match. Instead, we only know that like any other protein, this one has really long palindromic strings of nucleotides. To detect this protein, we need to first find the longest palindromic portion in an unknown sample.
We’ll be provided with a DNA generated protein sequence in the form of a string. Our task will be to locate and isolate the portion that has the nucleotides lined up as the longest palindrome to identify the correct protein.
Solution
A palindrome is a string that reads the same backwards as forwards. For example, str = abba is a palindrome, but str' = abcd is not. Although there can be multiple palindromes in the input string, we have to find the longest one. There are two ways we can check if a string is a palindrome:
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Start two pointers from each end of the string. Move towards the center while checking that the element ...