[LeetCode]题解（python）：093 Restore IP Addresses

题目来源

https://leetcode.com/problems/restore-ip-addresses/

Given a string containing only digits, restore it by returning all possible valid IP address combinations.

For example:
Given "25525511135",

return ["255.255.11.135", "255.255.111.35"]. (Order does not matter)

题意分析

Input:一串数字

Output:可能的ip

Conditions:符合0~255

题目思路

用dfs，要注意考虑0.0.0.0的情况，不考虑00.00.00.00这样多个0的

AC代码（Python）

 1 class Solution(object):
 2     def restoreIpAddresses(self, s):
 3         """
 4         :type s: str
 5         :rtype: List[str]
 6         """
 7         def dfs(s, sub, ips, ip):
 8             if sub == 4:
 9                 if s == "":
10                     ips.append(ip[1:])
11                 return
12             for i in range(1,4):
13                 if i <= len(s):
14                     if int(s[:i]) <= 255:
15                         dfs(s[i:], sub + 1, ips, ip+"."+s[:i])
16                     if s[0] == "0":
17                         break
18         ips = []
19         dfs(s, 0, ips, "")
20         return ips

 

posted @ 2016-05-03 17:35  loadofleaf  Views(259)  Comments(0)  Edit  收藏  举报