93_restore_IP_addresses.py

class Solution:
    def restoreIpAddresses(self, s: str) -> List[str]:

        def backtracking(tmp: List[str], begin: int) -> None:
            if begin == len(s):
                if len(tmp) == 4:
                    ans.append('.'.join(tmp))
                else:
                    return
            else:
                for i in range(begin, min(begin+3, len(s))):
                    tmp_str = s[begin: i+1]
                    if (len(tmp_str) > 1) and ((tmp_str[0] == '0') or (int(tmp_str) > 255)):
                        continue
                    else:
                        backtracking(tmp+[tmp_str], i+1)
        
        if (len(s) < 4) or (len(s) > 12):
            return [] 
        ans = []
        backtracking([], 0)
        return ans

'''
    This is my personal record of solving Leetcode Problems. 
    If you have any questions, please discuss them in [Issues](https://github.com/mengxinayan/leetcode/issues).
    Copyright (C) 2020-2022  mengxinayan

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
'''