def __create_input(self, main_root):
		content = self.__manager.load_content()
		input_dir = os.path.join(main_root,'input')
		try:
			content.get(self.__task.data['id'], 'input', os.path.join(main_root, 'input'))
		except:
			safe_mkdir(input_dir)
def addOperators(self, num, target):
        """
        Adapted from https://leetcode.com/discuss/58614/java-standard-backtrace-ac-solutoin-short-and-clear

        Algorithm:
        1. DFS
        2. Special handling for multiplication
        3. Detect invalid number with leading 0's
        :type num: str
        :type target: int
        :rtype: List[str]
        """
        ret = []
        self.dfs(num, target, 0, "", 0, 0, ret)
        return ret