<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 solve(int index , int n , string s , vector<string>& ans , int num , string output) {
        if(index >= n) {
            if(num == 5){
                output.pop_back();
                ans.push_back(output);
            }
            
            return ;
        }
        string store = output;
        string dummy;
        for(int i = index ; i < n ; i++) {
            dummy.push_back(s[i]);
            if(stoi(dummy) > 255) {
                break;
            }
            if(dummy == "0") {
                output.append(dummy);
                output.push_back('.');
                solve(i+1 , n , s , ans , num+1 , output);
                break;
            }
            else if(stoi(dummy) >= 0 && stoi(dummy) <= 255) {
                output.append(dummy);
                output.push_back('.');
                solve(i+1 , n , s , ans , num+1 , output);
                output = store;
            }
        }
    }
    vector<string> restoreIpAddresses(string s) {
     
        vector<string> ans;
        int n = s.length();
        string output;
        solve(0 , n , s , ans , 1 , output);
        
        return ans;
    }
};
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