1 def quchong(S):
2 str1=[""]
3 for i in S:
4 if i == str1[-1]:
5 str1.pop()
6 else:
7 str1.append(i)
8 print(''.join(str1))
9 quchong("daaba")
10 quchong("bbaca")
1 dba
2 aca