Minimum String Length After Removing

lcpy gen -n 2696   # by problem number
lcpy gen -s minimum_string_length_after_removing_substrings   # by problem name

Input: s = "ABFCACDB"
Output: 2
Explanation: We can do the following operations:
- Remove the substring "ABFCACDB", so s = "FCACDB".
- Remove the substring "FCACDB", so s = "FCAB".
- Remove the substring "FCAB", so s = "FC".
So the resulting length of the string is 2.
It can be shown that it is the minimum length that we can obtain.

Input: s = "ACBBD"
Output: 5
Explanation: We cannot do any operations on the string so the length remains the same.

class Solution:
    # Time: O(n)
    # Space: O(n)
    def min_length(self, s: str) -> int:
        stack: list[str] = []
        for char in s:
            if stack and ((stack[-1] == "A" and char == "B") or (stack[-1] == "C" and char == "D")):
                stack.pop()
            else:
                stack.append(char)
        return len(stack)