# # 【LeetCode】468. Validate IP Address 解题报告（Python）

## # 题目描述：

Write a function to check whether an input string is a valid IPv4 address or IPv6 address or neither.

IPv4 addresses are canonically represented in dot-decimal notation, which consists of four decimal numbers, each ranging from 0 to 255, separated by dots ("."), e.g.,`172.16.254.1`;

Besides, leading zeros in the IPv4 is invalid. For example, the address `172.16.254.01` is invalid.

IPv6 addresses are represented as eight groups of four hexadecimal digits, each group representing 16 bits. The groups are separated by colons ("😊. For example, the address `2001:0db8:85a3:0000:0000:8a2e:0370:7334` is a valid one. Also, we could omit some leading zeros among four hexadecimal digits and some low-case characters in the address to upper-case ones, so `2001:db8:85a3:0:0:8A2E:0370:7334` is also a valid IPv6 address(Omit leading zeros and using upper cases).

However, we don't replace a consecutive group of zero value with a single empty group using two consecutive colons (:😃 to pursue simplicity. For example, `2001:0db8:85a3::8A2E:0370:7334` is an invalid IPv6 address.

Besides, extra leading zeros in the IPv6 is also invalid. For example, the address `02001:0db8:85a3:0000:0000:8a2e:0370:7334` is invalid.

Note: You may assume there is no extra space or special characters in the input string.

Example 1:

``````Input: "172.16.254.1"

Output: "IPv4"

Explanation: This is a valid IPv4 address, return "IPv4".
``````

Example 2:

``````Input: "2001:0db8:85a3:0:0:8A2E:0370:7334"

Output: "IPv6"

Explanation: This is a valid IPv6 address, return "IPv6".
``````

Example 3:

``````Input: "256.256.256.256"

Output: "Neither"

``````

## # 解题方法

``````class Solution(object):
"""
:type IP: str
:rtype: str
"""
if '.' in IP and self.checkIPv4(IP):
return "IPv4"
elif ':' in IP and self.checkIPv6(IP):
return "IPv6"
else:
return "Neither"

def checkIPv4(self, IP):
numbers = IP.split('.')
if len(numbers) != 4: return False
for num in numbers:
if not num or (not num.isdecimal()) or (num[0] == '0' and len(num) != 1) or int(num) > 255:
return False
return True

def checkIPv6(self, IP):
IP = IP.lower()
valid16 = "0123456789abcdef"
if "::" in IP: return False
numbers = IP.split(':')
if len(numbers) > 8: return False
for num in numbers:
if not num: continue
if len(num) >= 5: return False
for n in num:
if n not in valid16:
return False
return True
``````

## # 日期

2018 年 6 月 13 日 ———— 腾讯赛圆满结束！两个月修得正果哈哈～～