LeetCode-in-Java

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 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 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 ':'.

Solution

public class Solution {
    private static final String NEITHER = "Neither";

    public String validIPAddress(String ip) {
        if (ip.isEmpty()) {
            return NEITHER;
        }
        String[] arr = ip.split("\\.", -1);
        String[] arr1 = ip.split(":", -1);
        if (arr.length == 4) {
            for (String num : arr) {
                try {
                    if ((num.length() > 1 && num.startsWith("0")) || Integer.parseInt(num) > 255) {
                        return NEITHER;
                    }
                } catch (Exception e) {
                    return NEITHER;
                }
            }
            return "IPv4";
        } else if (arr1.length == 8) {
            for (String num : arr1) {
                if (num.isEmpty() || num.length() > 4) {
                    return NEITHER;
                }
                for (int j = 0; j < num.length(); j++) {
                    char ch = num.charAt(j);
                    if (ch > 9
                            && (Character.isLowerCase(ch) && ch > 'f'
                                    || Character.isUpperCase(ch) && ch > 'F')) {
                        return NEITHER;
                    }
                }
            }
            return "IPv6";
        }
        return NEITHER;
    }
}

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