Leetcode 394. 字符串解码(中等)

class Solution:
    def decodeString(self, s: str) -> str:
        stack = []
        for c in s:
            if c == ']':
                repeatStr = ''
                repeatCount = ''
                while stack and stack[-1] != '[':
                    repeatStr = stack.pop() + repeatStr
                stack.pop() # pop 掉 "["
                while stack and stack[-1].isdigit():
                    repeatCount = stack.pop() + repeatCount
                stack.append(repeatStr * int(repeatCount))
            else:
                stack.append(c)
        return "".join(stack)