LeetCodeQuestionsAndAnswers/468_Validate_IP_Address.txt at main · anant7210/LeetCodeQuestionsAndAnswers · GitHub

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/* 468. Validate IP Address

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 1:

Input: IP = "172.16.254.1"
Output: "IPv4"
Explanation: This is a valid IPv4 address, return "IPv4".
Example 2:

Input: IP = "2001:0db8:85a3:0:0:8A2E:0370:7334"
Output: "IPv6"
Explanation: This is a valid IPv6 address, return "IPv6".
Example 3:

Input: IP = "256.256.256.256"
Output: "Neither"
Explanation: This is neither a IPv4 address nor a IPv6 address.
Example 4:

Input: IP = "2001:0db8:85a3:0:0:8A2E:0370:7334:"
Output: "Neither"
Example 5:

Input: IP = "1e1.4.5.6"
Output: "Neither"


Constraints:

IP consists only of English letters, digits and the characters '.' and ':'.

*/
class Solution {
    public String validIPAddress(String IP) {
        if(checkIPV4(IP)) {
            return "IPv4";
        }
        else if(checkIPV6(IP)) {
            return "IPv6";
        }
        else {
            return "Neither";
        }
    }

    private boolean checkIPV4(String IP) {
        int i = 0;
        int temp = 0;
        int t = 0;
        int cDot = 0;
        while(i < IP.length()) {
            if((IP.charAt(i) < 48 || IP.charAt(i) > 57) && IP.charAt(i) != '.') {
                return false;
            }
            if(IP.charAt(i) == '.' && (cDot == 3))
               return false;
            if(IP.charAt(i) == '.') {
                if(t > 255 || temp == 0)
                    return false;
                temp = 0;
                t = 0;
                cDot++;
                i++;
                continue;
            }
            if(IP.charAt(i) == '0' && t == 0 && i < IP.length() - 1 && IP.charAt(i + 1) != '.')
                return false;
            t = t * 10 + (int)(IP.charAt(i)) - 48;
            temp++;
            if(temp > 3)
                return false;
            i++;
        }
        if(cDot < 3 ||  temp == 0 )
            return false;
        if(t > 255)
            return false;
        return true;
    }

    private boolean checkIPV6(String IP) {
        int i = 0;
        int temp = 0;
        int cColon = 0;
        while(i < IP.length()) {
            char curr = IP.charAt(i);
            if((curr < 48 || curr > 57) && (curr < 65 || curr > 70) && (curr < 97 || curr > 102) && IP.charAt(i) != ':') {
                return false;
            }
            if(IP.charAt(i) == ':') {
                if(cColon == 7)
                    return false;
                if(temp > 4 || temp < 1)
                    return false;
                temp = 0;
                cColon++;
                i++;
                continue;
            }
            temp++;
            i++;
        }
        if(cColon < 7 || temp > 4 || temp < 1)
            return false;
        return true;
    }
}