IPv4 or IPv6? (Or Neither?)

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Not a hard problem just annoying with all the different corner cases. Lots of missing, fixing and retrying. Code is down below, cheers, and love, ACC.

Validate IP Address - LeetCode

468. Validate IP Address
Medium

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 xi cannot 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 ':'.
Accepted
149,578
Submissions
559,091

public string ValidIPAddress(string queryIP)
{
    if (IsIPv4(queryIP)) return "IPv4";
    if (IsIPv6(queryIP)) return "IPv6";
    return "Neither";
}

private bool IsIPv6(string str)
{
    if (String.IsNullOrEmpty(str)) return false;

    string[] parts = str.Split(new char[] { ':' });
    if (parts == null || parts.Length != 8) return false;

    string valid = "0123456789abcdefABCDEF";
    foreach (string part in parts)
    {
        if (part.Length < 1 || part.Length > 4) return false;
        foreach (char c in part)
            if (!valid.Contains(c)) return false;
    }

    return true;
}

private bool IsIPv4(string str)
{
    if (String.IsNullOrEmpty(str)) return false;

    string[] parts = str.Split(new char[] { '.' });
    if (parts == null || parts.Length != 4) return false;

    foreach (string part in parts)
    {
        if (part.StartsWith("0") && part.Length > 1) return false;
        int temp = 0;
        if (!Int32.TryParse(part, out temp)) return false;
        if (temp < 0 || temp > 255) return false;
        if (temp > 0 && part.StartsWith("0")) return false;
    }

    return true;
}

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