Problem: Given a string IP, 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 xi cannot contain leading zeros. For example, "192.168.1.1" and "192.168.1.0" are valid IPv4 addresses but "192.168.01.1", while "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, lower-case 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:
Input: IP = "172.16.254.1" Output: "IPv4" Explanation: This is a valid IPv4 address, return "IPv4".
Input: IP = "2001:0db8:85a3:0:0:8A2E:0370:7334" Output: "IPv6" Explanation: This is a valid IPv6 address, return "IPv6".
Input: IP = "256.256.256.256" Output: "Neither" Explanation: This is neither a IPv4 address nor a IPv6 address.
Input: IP = "2001:0db8:85a3:0:0:8A2E:0370:7334:" Output: "Neither"
Input: IP = "1e1.4.5.6" Output: "Neither"
Approach: Nothing to explain here. We are just verifying the conditions which are given in the problem statement. That's all!
Implementation in C#:
public static string ValidIPAddress(string IP)
{
string[] arr = IP.Split('.');
if (arr.Length == 4)
{
if (ValidIPv4(arr))
{
return "IPv4";
}
}
else
{
arr = IP.Split(':');
if (arr.Length == 8)
{
if (ValidIPv6(arr))
{
return "IPv6";
}
}
}
return "Neither";
}
private static bool ValidIPv6(string[] sections)
{
foreach (string section in sections)
{
if (string.IsNullOrWhiteSpace(section) || section.Length > 4)
{
return false;
}
foreach(char ch in section)
{
if (!char.IsDigit(ch))
{
char alphaChar = char.ToLower(ch);
if (alphaChar < 'a' || alphaChar > 'f')
{
return false;
}
}
}
}
return true;
}
private static bool ValidIPv4(string[] sections)
{
foreach(string section in sections)
{
if (string.IsNullOrWhiteSpace(section)
|| (section[0] == '0' && section.Length > 1)
|| section.Length > 3)
{
return false;
}
int num;
if (int.TryParse(section, out num))
{
if (num < 0 || num > 255)
{
return false;
}
}
else
{
return false;
}
}
return true;
}
Complexity: O(n)
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