<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>finalans ;
    string curr ;

    vector<string>split(string s, char ch){
          string curr = "";
          vector<string>ans ;
          for(int i =0 ; i<s.size(); i++){
            if(s[i] != ch){
                curr += s[i];
            }
            else{
                 ans.push_back(curr);
                 curr = "";
            }
          }
          if(curr.size() != 0){
             ans.push_back(curr);
          }
          return ans ;   
    }

    bool is_valid(string ip){
         vector<string>res = split(ip,'.');
         if(res.size() < 4)return false;
         for(auto v : res){
            long long y = stoll(v);
            if(y > 255)return false;
            if(v.length() >1 && v[0] == '0')return false;
         }
         return true ;
    }

    void rec(int level, int k, string &s){

          if(k>3)return ;

          if(level == s.size()){
           
             if(k ==3 && is_valid(curr)){
                    finalans.push_back(curr);
                    return ;
             }
             else{
                return ;
             }
          }

        
        curr += s[level];
        rec(level+1,k,s);
        curr.pop_back();


        curr += s[level];
        curr += '.';
        rec(level+1,k+1,s);
        curr.pop_back();
        curr.pop_back();

    }

    vector<string> restoreIpAddresses(string s) {
         finalans.clear();
         rec(0,0,s);
         return finalans;
    }
};
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