求大佬们帮忙看一下第二题，我用的是DFS，我在自己的IDE，case全过了，但是提交后零分，不知道是什么问题 import sys if __name__ == "__main__":     s = int(sys.stdin.readline().strip())     if s==0:         print('{')         print('}')     for _ in range(s):         girl=sys.stdin.readline().strip()         boy=sys.stdin.readline().strip()         res=[]         def helper(girl,girl_new,way):             if len(girl_new)>len(boy):                 return             if ''.join(girl_new)==boy:                 res.append(way)                 return             if len(girl)>0:                 helper(girl[1:],girl_new,way+['d'])                 helper(girl[1:],[girl[0]]+girl_new,way+['l'])                 helper(girl[1:],  girl_new+[girl[0]], way+['r'])         helper(girl,[],[])         print('{')         if res:             res=sorted(res)             for r in res:                 print(' '.join(r)+' ')         print('}')