<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:

    vector<string> restoreIpAddresses(string s) {

        vector<string> ans;

        string k;

        for(int a=1;a<=3;a++){

            for(int b=1;b<=3;b++){

                for(int c=1;c<=3;c++){

                    for(int d=1;d<=3;d++){

                        if(a+b+c+d==s.length()){

                        int s1=stoi(s.substr(0, a));

                        int s2=stoi(s.substr(a, b));

                        int s3=stoi(s.substr(a+b, c));

                        int s4=stoi(s.substr(a+b+c, d));

                        if(s1<=255&&s2<=255&&s3<=255&&s4<=255)

                        {

                            if((k=to_string(s1)+"."+to_string(s2)+"."+to_string(s3)+"."+to_string(s4)).length()>=s.length()+3)

                            ans.push_back(k);

                        }

                        }

                    }

                }

            }

        }

        return ans;

    }

};
        
    

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