<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];
    bool flag = false;
    bool containkey(char i){
        return (links[i-'a']!=NULL);
    }
    void insertKey(char i){
        links[i-'a'] = new Node();
    }
    Node* next(char i){
        return links[i-'a'];
    }
    void setEnd(){
        flag = true;
    }
    bool isEnd(){
        return flag;
    }
};
class Trie {
private: Node* root;
public:
    Trie() {
        root = new Node();
    }
    
    void insert(string word) {
        Node* node=root;
        for(auto i:word){
            if(!node->containkey(i)){
                node->insertKey(i);
            }
            node = node->next(i);
        }
        node->setEnd();
    }
    
    bool search(string word) {
        Node* node=root;
        for(auto i:word){
            if(!node->containkey(i)){
                return false;
            }
            node = node->next(i);
        }
        return node->isEnd();

    }
    
    bool startsWith(string prefix) {
        Node* node=root;
        for(auto i:prefix){
            if(!node->containkey(i)){
                return false;
            }
            node = node->next(i);
        }
        return true;
    }
};
class Solution {
public:
    string longestWord(vector<string>& words) {
        vector<pair<int,string>> v;
        for(auto i:words){
            v.push_back({i.length(),i});
        }
        sort(v.begin(),v.end());
        string ans="";
        Trie* obj = new Trie();
        for(auto i:v){
           bool f=true;
                string word = i.second;
                int l=i.first;
            string x= "";
            for(int j=0;j<word.length()-1;j++){
                x+=word[j];
                if(!obj->search(x)){
                    f=false;
                    break;
                }
            }
            cout<<word<<" "<<f<<endl;
            if(f ){
                if(l>ans.length() or (l==ans.length() and ans>word)){
                    ans=word;
                }
            }
            obj->insert(i.second);
        }
        return ans;
        
        
        
    }
};
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