已投递 刷题500左右吧 ``` # bfs tree stru of folder import os from os.path import isfile, join, basename class folder:     def __init__(self,path):         self.path=path         self.subfolders=[]     def addfolder(self,subfolder):         self.subfolders.append(subfolder)     def pprint(self,ind=0):         print("    "*ind+basename(self.path))         for subfolder in self.subfolders:             subfolder.pprint(ind+1) parent=folder(".") queue = [] queue.insert(0,parent) while queue:     cur = queue.pop()     for f in os.listdir(cur.path):         fabspath = join(cur.path,f)         if not isfile(fabspath):             subfolder = folder(fabspath)             cur.addfolder(subfolder)             queue.insert(0,subfolder) parent.pprint() ```