<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>

bool checker4(const string& x) {
    if (x.length() < 1 || x.length() > 3) {
        return false;
    }
    if (x[0] == '0' && x.length() > 1) {
        return false;
    }
    int16_t num = 0;
    for (const auto c : x) {
        if (c < '0' || c > '9') {
            return false;
        }
        num = num * 10 + c - '0';
        if (num > 255) {
            return false;
        }
    }
    return true;
}
bool checker6(const string& x) {
    if (x.length() < 1 || x.length() > 4) {
        return false;
    }
    for (const auto c : x) {
        if ((c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F')) {
            continue;
        } else {
            return false;
        }
    }
    return true;
}

class Solution {
public:
    bool check(const string& queryIP, size_t numSec, char deli, bool (*checker)(const string&)) {
        size_t pos = 0;
        for (size_t i = 0; i < numSec; ++i) {
            string x;
            if (i < numSec - 1) {
                size_t posNext = queryIP.find(deli, pos);
                if (posNext == queryIP.npos) {
                    return false;
                }
                x = queryIP.substr(pos, posNext - pos);
                pos = posNext + 1;
            } else {
                x = queryIP.substr(pos);
            }
            if (!checker(x)) {
                return false;
            };
        }
        return true;
    }
    
    bool check4(const string& queryIP) {
        return check(queryIP, 4, '.', &checker4);
    }
    
    bool check6(const string& queryIP) {
        auto checker = [](const string& x) {
            
        };
        return check(queryIP, 8, ':', &checker6);
    }
    
    string validIPAddress(string queryIP) {
        if (check4(queryIP)) {
            return "IPv4";
        } else if (check6(queryIP)) {
            return "IPv6";
        } else return "Neither";
    }
};
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