<p>Given an array of strings <code>words</code> representing an English Dictionary, return <em>the longest word in</em> <code>words</code> <em>that can be built one character at a time by other words in</em> <code>words</code>.</p>

<p>If there is more than one possible answer, return the longest word with the smallest lexicographical order. If there is no answer, return the empty string.</p>

<p>Note that the word should be built from left to right with each additional character being added to the end of a previous word.&nbsp;</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> words = [&quot;w&quot;,&quot;wo&quot;,&quot;wor&quot;,&quot;worl&quot;,&quot;world&quot;]
<strong>Output:</strong> &quot;world&quot;
<strong>Explanation:</strong> The word &quot;world&quot; can be built one character at a time by &quot;w&quot;, &quot;wo&quot;, &quot;wor&quot;, and &quot;worl&quot;.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> words = [&quot;a&quot;,&quot;banana&quot;,&quot;app&quot;,&quot;appl&quot;,&quot;ap&quot;,&quot;apply&quot;,&quot;apple&quot;]
<strong>Output:</strong> &quot;apple&quot;
<strong>Explanation:</strong> Both &quot;apply&quot; and &quot;apple&quot; can be built from other words in the dictionary. However, &quot;apple&quot; is lexicographically smaller than &quot;apply&quot;.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= words.length &lt;= 1000</code></li>
	<li><code>1 &lt;= words[i].length &lt;= 30</code></li>
	<li><code>words[i]</code> consists of lowercase English letters.</li>
</ul>

struct Node
{
    Node* links[26];

};
class trie
{
    private:
        Node* root;
    public:
        trie()
        {
            root=new Node();
            for(int i=0;i<26;i++)
            {
                root->links[i]=nullptr;
            }
        }
        bool insert(string word)
        {
            Node* node=root;
            for(int i=0;i<word.length();i++)
            {
                if(!node->links[word[i]-'a'])
                {
                    if(i!=word.length()-1)
                    {
                        return false;
                    }
                    node->links[word[i]-'a']=new Node();
                }
                node=node->links[word[i]-'a'];
                
            }
            return true;
        }
};
class Solution {
public:
    string longestWord(vector<string>& words) 
    {
        sort(words.begin(), words.end());
        trie tr;
        string longest="";
        for(int i=0;i<words.size();i++)
        {
            bool flag=tr.insert(words[i]);
            if(flag)
            {
                if(words[i].length()>longest.length())
                {
                    longest=words[i];
                }
                else if(words[i].length()==longest.length() && words[i]<longest)
                {
                    longest=words[i];
                }
            }
        }
        return longest;
    }
};
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