Given a string queryIP, return "IPv4" if IP is a valid IPv4 address, "IPv6" if IP is a valid IPv6 address or "Neither" if IP is not a correct IP of any type.
A valid IPv4 address is an IP in the form "x1.x2.x3.x4" where 0 <= xi <= 255 and xicannot contain leading zeros. For example, "192.168.1.1" and "192.168.1.0" are valid IPv4 addresses while "192.168.01.1", "192.168.1.00", and "192.168@1.1" are invalid IPv4 addresses.
A valid IPv6 address is an IP in the form "x1:x2:x3:x4:x5:x6:x7:x8" where:
1 <= xi.length <= 4
xi is a hexadecimal string which may contain digits, lowercase English letter ('a' to 'f') and upper-case English letters ('A' to 'F').
Leading zeros are allowed in xi.
For example, "2001:0db8:85a3:0000:0000:8a2e:0370:7334" and "2001:db8:85a3:0:0:8A2E:0370:7334" are valid IPv6 addresses, while "2001:0db8:85a3::8A2E:037j:7334" and "02001:0db8:85a3:0000:0000:8a2e:0370:7334" are invalid IPv6 addresses.
Example 1:
Input: queryIP = "172.16.254.1"
Output: "IPv4"
Explanation: This is a valid IPv4 address, return "IPv4".
Example 2:
Input: queryIP = "2001:0db8:85a3:0:0:8A2E:0370:7334"
Output: "IPv6"
Explanation: This is a valid IPv6 address, return "IPv6".
Example 3:
Input: queryIP = "256.256.256.256"
Output: "Neither"
Explanation: This is neither a IPv4 address nor a IPv6 address.
Constraints:
queryIP consists only of English letters, digits and the characters '.' and ':'.
Solutions
Solution 1: Simulation
We can define two functions isIPv4 and isIPv6 to determine whether a string is a valid IPv4 address and IPv6 address.
The implementation of the function isIPv4 is as follows:
We first check if the string s ends with .. If so, s is not a valid IPv4 address, and we directly return false.
Then we split the string s by . into a string array ss. If the length of ss is not 4, s is not a valid IPv4 address, and we directly return false.
For each string t in the array ss, we check:
If the length of t is greater than 1 and the first character of t is 0, t is not a valid IPv4 address, and we directly return false.
If t is not a number or t is not in the range of 0 to 255, t is not a valid IPv4 address, and we directly return false.
If none of the above conditions are met, s is a valid IPv4 address, and we return true.
The implementation of the function isIPv6 is as follows:
We first check if the string s ends with :. If so, s is not a valid IPv6 address, and we directly return false.
Then we split the string s by : into a string array ss. If the length of ss is not 8, s is not a valid IPv6 address, and we directly return false.
For each string t in the array ss, we check:
If the length of t is less than 1 or greater than 4, t is not a valid IPv6 address, and we directly return false.
If the characters in t are not all between 0 and 9 and a and f (case insensitive), t is not a valid IPv6 address, and we directly return false.
If none of the above conditions are met, s is a valid IPv6 address, and we return true.
Finally, we call the isIPv4 and isIPv6 functions to determine if queryIP is a valid IPv4 address or IPv6 address. If it is neither, we return Neither.
The time complexity is $O(n)$, and the space complexity is $O(n)$. Where $n$ is the length of the string queryIP.