字符串解码

def solve():
    def decodeString(____):
        stack = []
        curr_str = '____'
        curr_num = ____
        for char in s:
            if char.isdigit():
                curr_num = curr_num * ____ + int(____)
            elif char == '____':
                stack.append((____))
                curr_str = '____'
                curr_num = ____
            elif char == '____':
                prev_str, num = stack.pop()
                curr_str = prev_str + curr_str * num
            else:
                curr_str += char
        return curr_str
    print(decodeString(____))