1. Using suffx trees, give an algorithm to find a longest common substring shared among three input strings: s1 of length n1, s2 of length n2 and s3 of length n3.
2. A non-empty string α is called a minimal unique substring of s if and only if it satisfies:
(i) α occurs exactly once in s (uniqueness),
(ii) all proper prefixes of α occur at least twice in s (mimimality), and
(iii) α≥l for some constant l.
Give an optimal algorithm to enumerate all minimal unique substrings of s.
3. Redundant sequence identification: Given a set of k DNA sequences, S = {s1,s2,.......,sk}, give an optimal algorithm to identify allsequences that are completely contained in (i.e., substrings of) at least one other sequence in S.
4. Collaborative
Let S = {s1,s2,...........,sk} denote a set of k genomes. The problem of fingerprinting is the task of identifying a shortest possible substring αi from each string si such that αi is unique to si -- i.e., no other genome in the set S has αi. Such an αi will be called a fingerprint of si.
(Note that it is OK for i to be present more than once within si.)
Give an algorithm to enumerate a fingerprint for each input genome, if one exists. Assume that no two input genomes are identical.
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