Validate IP Address
<p>Given a string <code>queryIP</code>, return <code>&quot;IPv4&quot;</code> if IP is a valid IPv4 address, <code>&quot;IPv6&quot;</code> if IP is a valid IPv6 address or <code>&quot;Neither&quot;</code> if IP is not a correct IP of any type.</p>

<p><strong>A valid IPv4</strong> address is an IP in the form <code>&quot;x<sub>1</sub>.x<sub>2</sub>.x<sub>3</sub>.x<sub>4</sub>&quot;</code> where <code>0 &lt;= x<sub>i</sub> &lt;= 255</code> and <code>x<sub>i</sub></code> <strong>cannot contain</strong> leading zeros. For example, <code>&quot;192.168.1.1&quot;</code> and <code>&quot;192.168.1.0&quot;</code> are valid IPv4 addresses while <code>&quot;192.168.01.1&quot;</code>, <code>&quot;192.168.1.00&quot;</code>, and <code>&quot;192.168@1.1&quot;</code> are invalid IPv4 addresses.</p>

<p><strong>A valid IPv6</strong> address is an IP in the form <code>&quot;x<sub>1</sub>:x<sub>2</sub>:x<sub>3</sub>:x<sub>4</sub>:x<sub>5</sub>:x<sub>6</sub>:x<sub>7</sub>:x<sub>8</sub>&quot;</code> where:</p>

<ul>
	<li><code>1 &lt;= x<sub>i</sub>.length &lt;= 4</code></li>
	<li><code>x<sub>i</sub></code> is a <strong>hexadecimal string</strong> which may contain digits, lowercase English letter (<code>&#39;a&#39;</code> to <code>&#39;f&#39;</code>) and upper-case English letters (<code>&#39;A&#39;</code> to <code>&#39;F&#39;</code>).</li>
	<li>Leading zeros are allowed in <code>x<sub>i</sub></code>.</li>
</ul>

<p>For example, &quot;<code>2001:0db8:85a3:0000:0000:8a2e:0370:7334&quot;</code> and &quot;<code>2001:db8:85a3:0:0:8A2E:0370:7334&quot;</code> are valid IPv6 addresses, while &quot;<code>2001:0db8:85a3::8A2E:037j:7334&quot;</code> and &quot;<code>02001:0db8:85a3:0000:0000:8a2e:0370:7334&quot;</code> are invalid IPv6 addresses.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> queryIP = &quot;172.16.254.1&quot;
<strong>Output:</strong> &quot;IPv4&quot;
<strong>Explanation:</strong> This is a valid IPv4 address, return &quot;IPv4&quot;.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> queryIP = &quot;2001:0db8:85a3:0:0:8A2E:0370:7334&quot;
<strong>Output:</strong> &quot;IPv6&quot;
<strong>Explanation:</strong> This is a valid IPv6 address, return &quot;IPv6&quot;.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> queryIP = &quot;256.256.256.256&quot;
<strong>Output:</strong> &quot;Neither&quot;
<strong>Explanation:</strong> This is neither a IPv4 address nor a IPv6 address.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>queryIP</code> consists only of English letters, digits and the characters <code>&#39;.&#39;</code> and <code>&#39;:&#39;</code>.</li>
</ul>
String
impl Solution {
    pub fn valid_ip_address(query_ip: String) -> String {
        if Self::is_ipv4(&query_ip) {
            return "IPv4".to_string();
        }
        if Self::is_ipv6(&query_ip) {
            return "IPv6".to_string();
        }
        "Neither".to_string()
    }

    fn is_ipv4(s: &str) -> bool {
        if s.ends_with('.') {
            return false;
        }
        let ss: Vec<&str> = s.split('.').collect();
        if ss.len() != 4 {
            return false;
        }
        for t in ss {
            if t.is_empty() || (t.len() > 1 && t.starts_with('0')) {
                return false;
            }
            match Self::convert(t) {
                Some(x) if x <= 255 => {
                    continue;
                }
                _ => {
                    return false;
                }
            }
        }
        true
    }

    fn is_ipv6(s: &str) -> bool {
        if s.ends_with(':') {
            return false;
        }
        let ss: Vec<&str> = s.split(':').collect();
        if ss.len() != 8 {
            return false;
        }
        for t in ss {
            if t.len() < 1 || t.len() > 4 {
                return false;
            }
            if !t.chars().all(|c| c.is_digit(16)) {
                return false;
            }
        }
        true
    }

    fn convert(s: &str) -> Option<i32> {
        let mut x = 0;
        for c in s.chars() {
            if !c.is_digit(10) {
                return None;
            }
            x = x * 10 + (c.to_digit(10).unwrap() as i32);
            if x > 255 {
                return Some(x);
            }
        }
        Some(x)
    }
}
