Leetcode -- 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)

The question is to give a string with a reasonable IP address and a list containing all reasonable IP addresses. We know that the IP address is composed of four parts and the reasonable range is 0.0.0.0 ~ 255.255.255.255.

The Code mainly has two functions:

Isvalid -- check whether it is reasonable. If it starts with 0, the string must be 0; otherwise, it must be greater than 0 and less than 255;

DFS-use the Deep Search Method to search for all possible combinations;

Therefore, the DFS method is used to search for all possible combinations. If valid is used during each search to the fourth part, this is a reasonable IP address and is added to the result list.

Pay attention to the details of generating IP addresses and Add. Or something.

The Python code is as follows:

 1 class RestoreIPAddress: 2  3     def isValid(self, src): 4         if src[0] == ‘0‘: 5             return src == ‘0‘ 6         return 255 >= int(src) > 0 7  8     def dfs(self, src, temp, res, count): 9         if count == 3 and self.isValid(src):10             res.append(temp + src)11             return12         for i in range(1, min(4, len(src))):13             sub = src[0:i]14             if self.isValid(sub):15                 self.dfs(src[i:], temp + sub + ‘.‘, res, count + 1)16 17     def restoreIpAddresses(self, s):18         if len(s) < 4 or len(s) > 12:19             return []20         res = []21         self.dfs(s, "", res, 0)22         # print(res)23         return res24 25 p = RestoreIPAddress()26 p.restoreIpAddresses("0000")

 

Leetcode -- Restore IP addresses