1. A string s is said to be periodic with a period α, if s is α^k for some k>2. (Note that α^k is the string formed by concatenating k times.) A DNA sequence s is called a tandem repeat if it is periodic. Given a DNA sequence s, determine if it is periodic, and if so, the values for α and k. Note that there could be more than one period for a periodic string. In such a case, you need to report the shortest period.

2. A non-empty string β is called a repeat prefix of a string s if ββ is a prefix of s. Give a linear time algorithm to find the longest repeat prefix of s.

Hint: Think of using lca queries.