Given a string
S containing only characters
b. A substring (contiguous fragment) of
is called a semi-alternating substring if it does not contain three identical consecutive characters.
In other words, it does not contain either 'aaa' or 'bbb' substrings. Note that the whole
S is its own substring.
This is a companion discussion topic for the original entry at https://algo.monster/problems/longest_semi_alternating_substring/