re.sub create a new string, not in place modification
class Solution(object):
def decodeString(self, s):
"""
:type s: str
:rtype: str
"""
while '[' in s:
s=re.sub(r'(\d+)\[([a-z]+)\]',lambda x:int(x.group(1))*x.group(2),s)
return s
my solution using stack
class Solution(object):
def decodeString(self, s):
"""
:type s: str
:rtype: str
"""
stack=[]
res=''
tokens=iter(re.findall(r'\d+|\[|\]|[a-z]+',s))
for token in tokens:
if token.isdigit():
stack.append(int(token))
next(tokens)
else:
if token==']':
temp=stack.pop()*stack.pop()
else:
temp=token
if stack and not isinstance(stack[-1],int):
stack[-1]+=temp
else:
stack.append(temp)
if stack:
res+=''.join(stack)
return res
