class Solution:
    def scoreOfParentheses(self, s: str) -> int:
        score_stack = [] # 存檔處
        cur_score = 0 # 目前工作區
        for c in s:
           if c == '(':
                score_stack.append(cur_score)  # 存檔
                cur_score = 0                  # 開新工作區
           else: # ')'
                prev_score = score_stack.pop()
                # +1 (工作區為 0) or *2 (工作區不為 0)
                if cur_score == 0:
                    cur_score += 1
                else:
                    cur_score = cur_score * 2
                cur_score += prev_score        # 更新上一層工作區總分 (第 0 層為最外層)

        return cur_score