题目地址：https://leetcode.com/problems/validate-ip-address/description/
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"
Explanation: This is neither a IPv4 address nor a IPv6 address.
题目大意
给出了IPv4和IPv6的地址规范，求一个字符串属于哪类地址，如果都不属于，那么返回"Neither"。
解题方法
其实这种题本身不难，更多的工作在于审题和测试吧。所以做这个题应该把题目中所有的IP都复制到Testcase中进行测试。
我趟了一个坑，题目说的"::"这种v6地址是不合法的。。好吧，谁让你是出题官。
另外一个坑，题目说不包含特殊符号，但是在v4地址中仍然出现了"1e5"这种测试用例。。
class Solution(object):
def validIPAddress(self, IP):
"""
: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
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