# Given two equal length strings, figure out if one is a rotation of the other. O(n)
# Given two polygons find out if they are similar polygons. O(n)
# Given a string, find it's longest periodic prefix. O(n log n) For aaabaaabcde the answer is aaabaaab

# Given a tree T with character labeled nodes and a given string P count how many downward a paths matching  P. O(n)

# Given a tree T with character labeled nodes and a given string P count how many downward paths match P. O(n)