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| class Solution(object):
def restoreIpAddresses(self, s):
"""
:type s: str
:rtype: List[str]
"""
result = []
self._restoreIpAddresses(0, s, [], result)
return result
def _restoreIpAddresses(self, length, s, ips, result):
if not s:
if length == 4:
result.append('.'.join(ips)) # 以.分隔作为字符串返回
return
if length == 4: # 分了4段，结束
return
# 取一位
self._restoreIpAddresses(length + 1, s[1:], ips + [s[:1]], result)
# 若要取2位及以上，要确保目前的第一位不能为0
if s[0] != '0':
if len(s) >= 2:
self._restoreIpAddresses(length + 1, s[2:], ips + [s[:2]], result)
if len(s) >= 3 and int(s[:3]) <= 255: # 若要取3位，则要保证小于255
self._restoreIpAddresses(length + 1, s[3:], ips + [s[:3]], result)
|