Minimum Length of String After Deleting Similar Ends

Given a string of 'a', 'b', and 'c', repeatedly delete a non-empty prefix and non-empty suffix that are runs of the same character and equal to each other (without overlapping) and return the minimum possible remaining length. This is a two-pointer/greedy problem of shrinking matching uniform ends until characters differ or the pointers cross (n up to 1e5).