<p>A <strong>valid IP address</strong> consists of exactly four integers separated by single dots. Each integer is between <code>0</code> and <code>255</code> (<strong>inclusive</strong>) and cannot have leading zeros.</p>

<ul>
	<li>For example, <code>&quot;0.1.2.201&quot;</code> and <code>&quot;192.168.1.1&quot;</code> are <strong>valid</strong> IP addresses, but <code>&quot;0.011.255.245&quot;</code>, <code>&quot;192.168.1.312&quot;</code> and <code>&quot;192.168@1.1&quot;</code> are <strong>invalid</strong> IP addresses.</li>
</ul>

<p>Given a string <code>s</code> containing only digits, return <em>all possible valid IP addresses that can be formed by inserting dots into </em><code>s</code>. You are <strong>not</strong> allowed to reorder or remove any digits in <code>s</code>. You may return the valid IP addresses in <strong>any</strong> order.</p>

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

<pre>
<strong>Input:</strong> s = &quot;25525511135&quot;
<strong>Output:</strong> [&quot;255.255.11.135&quot;,&quot;255.255.111.35&quot;]
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;0000&quot;
<strong>Output:</strong> [&quot;0.0.0.0&quot;]
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;101023&quot;
<strong>Output:</strong> [&quot;1.0.10.23&quot;,&quot;1.0.102.3&quot;,&quot;10.1.0.23&quot;,&quot;10.10.2.3&quot;,&quot;101.0.2.3&quot;]
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 20</code></li>
	<li><code>s</code> consists of digits only.</li>
</ul>

class Solution {
public:

    void solver(string & s, int it, int n, string cur, vector<string> & res, int cntr)
    {
        if(it == n && cntr == 4)
        {
            if(cur.back() == '.') cur.pop_back();

            res.push_back(cur);
            return;
        }

        string tmp;

        for(int i = it; i < n; i++)
        {
            tmp += s[i];

            if(s[it] == '0') { solver(s, i + 1, n, cur + "0.", res, cntr + 1); break; }

            if(tmp.size() <= 3 && stoi(tmp) < 256)
            {
                tmp.push_back('.');

                solver(s, i + 1, n, cur + tmp, res, cntr + 1);

                tmp.pop_back();
            }
        }
    }
    vector<string> restoreIpAddresses(string s)
    {
        vector<string> res;
        string tmp;
        int n = s.size();

        solver(s, 0, n, tmp, res, 0);

        return res;    
    }
};
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