Practice/Meta/Leetcode 468. Validate IP Address

Leetcode 468. Validate IP Address

CodingMust

Problem

You are building a network configuration validator. Given a string representing a potential IP address, determine whether it's a valid IPv4 address, a valid IPv6 address, or neither.

Return one of three strings:

• "IPv4" if the input is a valid IPv4 address
• "IPv6" if the input is a valid IPv6 address
• "Neither" if the input is not a valid IP address of either type

Requirements

IPv4 Address Rules:

1. Must contain exactly four decimal numbers (octets) separated by dots
2. Each octet must be a number from 0 to 255 (inclusive)
3. No leading zeros are allowed (except for the number 0 itself)
4. No extra leading or trailing characters
5. Each octet must contain only digits

IPv6 Address Rules:

1. Must contain exactly eight groups of hexadecimal digits separated by colons
2. Each group must contain 1 to 4 hexadecimal characters
3. Valid hexadecimal characters are 0-9, a-f, and A-F (case insensitive)
4. No extra leading or trailing characters
5. Leading zeros within a group are allowed

Constraints

• 1 ≤ queryIP.length ≤ 100
• queryIP consists only of English letters, digits, and the characters '.' and ':'
• Time complexity target: O(n) where n is the length of the string
• Space complexity target: O(1) excluding the output

Examples

Example 1:

Input: queryIP = "172.16.254.1" Output: "IPv4" Explanation: This string represents a valid IPv4 address with four octets, all within the valid range of 0-255.

Example 2:

Input: queryIP = "2001:0db8:85a3:0:0:8A2E:0370:7334" Output: "IPv6" Explanation: This is a valid IPv6 address with eight colon-separated groups of hexadecimal digits.

Example 3:

Input: queryIP = "192.168.1.00" Output: "Neither" Explanation: The last octet "00" has a leading zero, which violates IPv4 rules.

Example 4:

Input: queryIP = "02001:0db8:85a3:0:0:8A2E:0370:7334" Output: "Neither" Explanation: The first group has 5 characters, exceeding the maximum of 4 allowed in IPv6.

Example 5:

Input: queryIP = "192.168.1.1." Output: "Neither" Explanation: There's a trailing dot at the end, making it invalid.