<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>result;
   bool isValid(string str){
    if(str[0] == '0'){
        return false;
    }
     int val = stoi(str);

     return val<=255;
   }
   void solve(string& s, int idx, int parts, string temp){
     int n = s.length();

     if(idx == n && parts == 4){
        temp.pop_back();
        result.push_back(temp);
        return ;
     }
    if(idx+1 <= n){
    solve(s,idx+1,parts+1,temp + s.substr(idx,1) + ".");
    }
    if(idx+2 <= n && isValid(s.substr(idx,2))){
    solve(s,idx+2,parts+1,temp + s.substr(idx,2) + ".");
    }
     if(idx+3 <= n && isValid(s.substr(idx,3))){
    solve(s,idx+3,parts+1,temp + s.substr(idx,3) + ".");
     }


   }
    vector<string> restoreIpAddresses(string s) {
        
        int n = s.length();
        result.clear();

        if(n>12){
            return {};
        }
       string temp = "";
        int parts = 0;
        solve(s,0,parts,temp);

        return result;
    }
};
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