Gringotts and its strange passwords

Gringotts Wizarding Bank assigns a string and a vault number to each of its vault owners. A "score" is greatest sequence of continuous same letters. Vault number is equal to score that the string has. For example, the score for "aaa" is 1 and for "abaa" is 3. Each time they ask for opening their vault, their password is changed. The new password is a rearrangement of original string with same scor