<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> a;
    bool isvalid(string g){
        vector<string> wrds;
        stringstream ss(g);
        string temp;
        while(getline(ss,temp,'.'))
        {
            
            wrds.push_back(temp);
            
        }
        if(wrds.size()<4)return false;
        else{
            for(auto i:wrds){
                long long  x=stoll(i);
                if(x>255){
                    return false;
                }
                if(i.size()>1&&i[0]=='0'){
                    return false;
                }
            }
        }

        return true;

    }

    void rec(string s,int n,int level,string g,int dotcnt,int cnt){
        //pruning
        if(cnt>3)
        {
            return;
        }
        
        //base case
        if(level==n||dotcnt==4){
            if(g.back()=='.'){
                return;
            }
            if(isvalid(g)){
            a.push_back(g);
            }
            return;
        }


        //compute
        g.push_back(s[level]);
        g.push_back('.');
        rec(s,n,level+1,g,dotcnt+1,0);
        g.pop_back();
        rec(s,n,level+1,g,dotcnt,cnt+1);
        

        //save and return
    }

    vector<string> restoreIpAddresses(string s) {
        int n=s.size();
        rec(s,n,0,"",0,0);
        // for(auto i:a){
        //     cout<<i<<endl;
        // }
        // vector<string> aa;
        return a;
    }
};
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